Conditional handovers for wireless relay networks

ABSTRACT

A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through an Integrated Access and Backhaul (IAB) node, the wireless node comprising: receiver circuitry configured to: receive from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; receive from the IAB node a notification message comprising information representing a radio condition measured on a path between the IAB node and the wireless access node, and; processor circuitry configured to perform, based on the triggering condition and the information, a handover using the configuration of the candidate target cell.

TECHNICAL FIELD

The technology relates to wireless communications, and particularly to radio architecture and operation for resolving problematic conditions on wireless backhaul links.

BACKGROUND ART

A radio access network typically resides between wireless devices, such as user equipment (UEs), mobile phones, mobile stations, or any other device having wireless termination, and a core network. Example of radio access network types includes the GRAN, GSM radio access network; the GERAN, which includes EDGE packet radio services; UTRAN, the UMTS radio access network; E-UTRAN, which includes Long-Term Evolution; and g-UTRAN, the New Radio (NR).

A radio access network may comprise one or more access nodes, such as base station nodes, which facilitate wireless communication or otherwise provides an interface between a wireless terminal and a telecommunications system. A non-limiting example of a base station can include, depending on radio access technology type, a Node B (“NB”), an enhanced Node B (“eNB”), a home eNB (“HeNB”), a gNB (for a New Radio [“NR”] technology system), or some other similar terminology.

The 3rd Generation Partnership Project (“3GPP”) is a group that, e.g., develops collaboration agreements such as 3GPP standards that aim to define globally applicable technical specifications and technical reports for wireless communication systems. Various 3GPP documents may describe certain aspects of radio access networks. Overall architecture for a fifth generation system, e.g., the 5G System, also called “NR” or “New Radio”, as well as “NG” or “Next Generation”, is shown in FIG. 33, and is also described in 3GPP TS 38.300. The 5G NR network is comprised of NG RAN (Next Generation Radio Access Network) and 5GC (5G Core Network). As shown, NGRAN is comprised of gNBs (e.g., 5G Base stations) and ng-eNBs (i.e. LTE base stations). An Xn interface exists between gNB-gNB, between (gNB)-(ng-eNB) and between (ng-eNB)-(ng-eNB). The Xn is the network interface between NG-RAN nodes. Xn-U stands for Xn User Plane interface and Xn-C stands for Xn Control Plane interface. A NG interface exists between 5GC and the base stations (i.e. gNB & ng-eNB). A gNB node provides NR user plane and control plane protocol terminations towards the UE, and is connected via the NG interface to the 5GC. The 5G NR (New Radio) gNB is connected to AMF (Access and Mobility Management Function) and UPF (User Plane Function) in 5GC (5G Core Network).

In some cellular mobile communication systems and networks, such as Long-Term Evolution (LTE) and New Radio (NR), a service area is covered by one or more base stations, where each of such base stations may be connected to a core network by fixed-line backhaul links (e.g., optical fiber cables). In some instances, due to weak signals from the base station at the edge of the service area, users tend to experience performance issues, such as: reduced data rates, high probability of link failures, etc. A relay node concept has been introduced to expand the coverage area and increase the signal quality. As implemented, the relay node may be connected to the base station using a wireless backhaul link.

In 3rd Generation Partnership Project (3GPP), the relay node concept for the fifth generation (5G) cellular system has been discussed and standardized, where the relay nodes may utilize the same 5G radio access technologies (e.g., New Radio (NR)) for the operation of services to User Equipment (UE) (access link) and connections to the core network (backhaul link) simultaneously. These radio links may be multiplexed in time, frequency, and/or space. This system may be referred to as Integrated Access and Backhaul (IAB).

Some such cellular mobile communication systems and networks may comprise IAB-donors and IAB-nodes, where an IAB-donor may provide interface to a core network to UEs and wireless backhauling functionality to IAB-nodes; and additionally, an IAB-node may provide IAB functionality combined with wireless self-backhauling capabilities. IAB-nodes may need to periodically perform inter-IAB-node discovery to detect new IAB-nodes in their vicinity based on cell-specific reference signals (e.g., Synchronization Signal and PBCH block SSB). The cell-specific reference signals may be broadcasted on a Physical Broadcast Channel (PBCH) where packets may be carried or broadcasted on the Master Information Block (MIB) section.

Demand for wireless traffic has increased significantly over time and IAB systems are expected to be reliable and robust against various kinds of possible failures. Considerations have been given for IAB backhaul design. In particular, to provide methods and procedures to address radio link failures on the backhaul link.

What is needed are methods, apparatus, and/or techniques to cope with unfavorable conditions or problems on a wireless backhaul link.

SUMMARY OF INVENTION

In one example, a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through an Integrated Access and Backhaul (IAB) node, the wireless node comprising: receiver circuitry configured to: receive from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; receive from the IAB node a notification message comprising information representing a radio condition measured on a path between the IAB node and the wireless access node, and; processor circuitry configured to perform, based on the triggering condition and the information, a handover using the configuration of the candidate target cell.

In one example, a method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one Integrated Access and Backhaul (IAB) node, the method comprising: receiving from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell; receiving from the IAB node a notification message, and; making a determination of whether or not to execute a handover using the conditional handover configuration; wherein the triggering condition comprises at least one threshold value; the notification message comprises information representing a radio condition detected on a path between the wireless relay node and the wireless access node, and; the determination is based on the at least one threshold value and the information.

In one example, a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through an Integrated Access and Backhaul (IAB) node, the wireless access node comprising: processor circuitry configured to generate a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; transmitter circuitry configured to transmit the reconfiguration message to the wireless node; wherein the triggering condition and information are used by the wireless node to perform a handover using the configuration of the candidate target cell, the information representing a radio condition measured on a path between the IAB node and the wireless access node, and; the information is included in a notification message sent to the wireless node by the IAB node.

In one example, a method for a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through an Integrated Access and Backhaul (IAB) node, the method comprising: generating a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; transmitting the reconfiguration message to the wireless node; wherein: the triggering condition and information are used by the wireless node to perform a handover using the configuration of the candidate target cell, the information representing a radio condition measured on a path between the IAB node and the wireless access node, and; the information is included in a notification message sent to the wireless node by the IAB node.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other objects, features, and advantages of the technology disclosed herein will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the technology disclosed herein.

FIG. 1 is a diagrammatic view illustrating a mobile network infrastructure using 5G signals and 5G base stations.

FIG. 2 is a diagrammatic view depicting an example of functional block diagrams for the IAB-donor and the IAB-node.

FIG. 3 is a diagrammatic view illustrating Control Plane (C-Plane) and User Plane (U-Plane) protocols among the UE, IAB-nodes, and IAB-donor.

FIG. 4 is a functional block diagram of an example protocol stack configuration for the U-Plane.

FIG. 5A depicts a functional block diagram of an example protocol stack configuration for the C-Plane between an IAB-node connected to an IAB-donor.

FIG. 5B depicts a functional block diagram of an example configuration of the C-Plane protocol stack for an IAB-node connected to another IAB-node which is connected to an IAB-donor.

FIG. 5C depicts a functional block diagram of an example configuration of the C-Plane protocol stack for a UE's RRC signaling.

FIG. 6A depicts an example message sequence for an IAB-node to establish an RRC connection, followed by F1-AP* connection.

FIG. 6B depicts an example message sequence for IAB-node to establish an RRC connection with an IAB-donor, followed by the F1 setup procedure.

FIG. 7 is a diagrammatic view of an example scenario where an IAB-node detects a Radio Link Failure (RLF) on the upstream link to its parent node.

FIG. 8 illustrates an example flow of information transmit/receive and/or processing by a UE and/or IAB-node connected to a set of IAB-nodes in communication with an IAB-donor, for processing a notification of an RLF.

FIG. 9A illustrates an example flow of information transmit/receive and/or processing by a UE and/or IAB-node connected to a set of IAB-nodes in communication with an IAB-donor, based on receiving an Upstream RLF notification.

FIG. 9B illustrates another example flow of information transmit/receive and/or processing by a UE and/or IAB-node connected to a set of IAB-nodes in communication with an IAB-donor, based on not having received an Upstream RLF notification.

FIG. 10 is a diagrammatic view illustrating an example of a radio protocol architecture for the control and user planes in a mobile communications network.

FIG. 11 is a diagrammatic view showing another example diagram of a telecommunications system in which a conditional autonomous handover may be performed for resolving a wireless link backhaul condition.

FIG. 12 is a diagrammatic view showing an example, non-limiting more detailed implementation of at least portions of the system of FIG. 11.

FIG. 13 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a wireless access node of FIG. 11.

FIG. 14 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a child node of FIG. 11.

FIG. 15 depicts example, basic, representative acts or steps of a message flow for the system scenario shown in FIG. 11.

FIG. 16 is a diagrammatic view showing another example diagram of a telecommunications system in wherein a wireless link backhaul condition may be resolved when redundant links are utilized.

FIG. 17 is a diagrammatic view showing an example, non-limiting more detailed implementation of at least portions of the system of FIG. 16.

FIG. 18 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a wireless access node of FIG. 16.

FIG. 19 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a child node of FIG. 16.

FIG. 20A depicts example, basic, representative acts or steps of a message flow for a first example system scenario shown in FIG. 16.

FIG. 20B depicts example, basic, representative acts or steps of a message flow for a first example system scenario shown in FIG. 16.

FIG. 21 is a diagrammatic view showing another example diagram of a telecommunications system in which a conditional autonomous handover may be performed using information from a conditional handover configuration message and information from a notification of radio conditions.

FIG. 22 is a diagrammatic view showing an example, non-limiting more detailed implementation of at least portions of the system of FIG. 12.

FIG. 23A is a diagrammatic view showing basic pertinent portion or information element of conditional handover configuration messages according to various example implementations.

FIG. 23B is a diagrammatic view showing basic pertinent portion or information element of conditional handover configuration messages according to various example implementations.

FIG. 23C is a diagrammatic view showing basic pertinent portion or information element of conditional handover configuration messages according to various example implementations.

FIG. 23D is a diagrammatic view showing basic pertinent portion or information element of conditional handover configuration messages according to various example implementations.

FIG. 23E is a diagrammatic view showing basic pertinent portion or information element of conditional handover configuration messages according to various example implementations.

FIG. 24A is a diagrammatic view showing various type of comparisons that may be performed by a handover controller of an Integrated Access and Backhaul (IAB) node according to various corresponding implementations of the system of FIG.

FIG. 24B is a diagrammatic view showing various type of comparisons that may be performed by a handover controller of an Integrated Access and Backhaul (IAB) node according to various corresponding implementations of the system of FIG.

FIG. 24C is a diagrammatic view showing various type of comparisons that may be performed by a handover controller of an Integrated Access and Backhaul (IAB) node according to various corresponding implementations of the system of FIG.

FIG. 25 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a wireless access node of FIG. 21.

FIG. 26 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a child node of FIG. 21.

FIG. 27 is a diagrammatic view showing another example diagram of a telecommunications system in which information of radio link failure (RLF) is reported to a wireless access node.

FIG. 28 is a diagrammatic view showing an example, non-limiting more detailed implementation of at least portions of the system of FIG. 27.

FIG. 29A is a diagrammatic view showing basic pertinent portion or information element of a failure information message according to various example implementations.

FIG. 29B is a diagrammatic view showing basic pertinent portion or information element of a failure information message according to various example implementations.

FIG. 29C is a diagrammatic view showing basic pertinent portion or information element of a failure information message according to various example implementations.

FIG. 30 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a wireless access node of FIG. 27.

FIG. 31 is a flowchart showing example, non-limiting, basic acts or steps that may be performed by a wireless node of FIG. 27.

FIG. 32 is a diagrammatic view showing example elements comprising electronic machinery which may comprise a wireless terminal, a radio access node, and a core network node according to an example embodiment and mode.

FIG. 33 is a diagrammatic view of overall architecture for a 5G New Radio system.

DESCRIPTION OF EMBODIMENTS

In one of its example aspects, the technology disclosed herein concerns a wireless terminal which communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one wireless relay node. In a basic embodiment and mode the wireless terminal comprises receiver circuitry, processor circuitry, and transmitter circuitry. The receiver circuitry is configured to receive from the wireless access node a conditional handover configuration message comprising a triggering condition, and to receive from the wireless relay node a notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node. The processor circuitry is configured to make a determination of whether or not to execute a handover based on the triggering condition and the information representing the radio condition. Methods for operating such a wireless terminal are also provided.

In another of its example aspects, the technology disclosed herein concerns a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless terminal through at least one wireless relay node. In a basic embodiment and mode the wireless access node comprises processor circuitry and transmitter circuitry. The processor circuitry is configured to generate a conditional handover configuration message comprising a triggering condition. The transmitter circuitry is configured to transmit the conditional handover configuration message to the wireless terminal. A notification message is sent by the wireless relay node to the wireless terminal, the notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node. The triggering condition and the information representing the radio condition enable the wireless terminal to make a determination of whether or not the wireless terminal executes a handover. Methods for operating such a wireless access node are also provided.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the technology disclosed herein. However, it will be apparent to those skilled in the art that the technology disclosed herein may be practiced in other embodiments that depart from these specific details. That is, those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the technology disclosed herein and are included within its spirit and scope. In some instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the technology disclosed herein with unnecessary detail. All statements herein reciting principles, aspects, and embodiments of the technology disclosed herein, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

Thus, for example, it will be appreciated by those skilled in the art that block diagrams herein can represent conceptual views of illustrative circuitry or other functional units embodying the principles of the technology. Similarly, it will be appreciated that any flow charts, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

As used herein, the term “core network” can refer to a device, group of devices, or sub-system in a telecommunication network that provides services to users of the telecommunications network. Examples of services provided by a core network include aggregation, authentication, call switching, service invocation, gateways to other networks, etc.

As used herein, the term “wireless terminal” can refer to any electronic device used to communicate voice and/or data via a telecommunications system, such as (but not limited to) a cellular network. Other terminology used to refer to wireless terminals and non-limiting examples of such devices can include user equipment terminal, UE, mobile station, mobile device, access terminal, subscriber station, mobile terminal, remote station, user terminal, terminal, subscriber unit, cellular phones, smart phones, personal digital assistants (“PDAs”), laptop computers, tablets, netbooks, e-readers, wireless modems, etc.

As used herein, the term “access node”, “node”, or “base station” can refer to any device or group of devices that facilitates wireless communication or otherwise provides an interface between a wireless terminal and a telecommunications system. A non-limiting example of a base station can include, in the 3GPP specification, a Node B (“NB”), an enhanced Node B (“eNB”), a home eNB (“HeNB”), a gNB (for a New Radio [“NR”] technology system), or some other similar terminology.

As used herein, the term “telecommunication system” or “communications system” can refer to any network of devices used to transmit information. A non-limiting example of a telecommunication system is a cellular network or other wireless communication system.

As used herein, the term “cellular network” or “cellular radio access network” can refer to a network distributed over cells, each cell served by at least one fixed-location transceiver, such as a base station. A “cell” may be any communication channel that is specified by standardization or regulatory bodies to be used for International Mobile Telecommunications-Advanced (“IMTAdvanced”). All or a subset of the cell may be adopted by 3GPP as licensed bands (e.g., frequency band) to be used for communication between a base station, such as a Node B, and a UE terminal. A cellular network using licensed frequency bands can include configured cells. Configured cells can include cells of which a UE terminal is aware and in which it is allowed by a base station to transmit or receive information. Examples of cellular radio access networks include E-UTRAN, and any successors thereof (e.g., NUTRAN).

Any reference to a “resource” herein means “radio resource” unless otherwise clear from the context that another meaning is intended. In general, as used herein a radio resource (“resource”) is a time-frequency unit that can carry information across a radio interface, e.g., either signal information or data information. An example of a radio resource occurs in the context of a “frame” of information that is typically formatted and prepared, e.g., by a node. In Long Term Evolution (LTE) a frame, which may have both downlink portion(s) and uplink portion(s), is communicated between the base station and the wireless terminal. Each LTE frame may comprise plural subframes. For example, in the time domain, a 10 ms frame consists of ten one millisecond subframes. An LTE subframe is divided into two slots (so that there are thus 20 slots in a frame). The transmitted signal in each slot is described by a resource grid comprised of resource elements (RE). Each column of the two dimensional grid represents a symbol (e.g., an OFDM symbol on downlink (DL) from node to wireless terminal; an SC-FDMA symbol in an uplink (UL) frame from wireless terminal to node). Each row of the grid represents a subcarrier. A resource element (RE) is the smallest time-frequency unit for downlink transmission in the subframe. That is, one symbol on one sub-carrier in the sub-frame comprises a resource element (RE) which is uniquely defined by an index pair (k,l) in a slot (where k and 1 are the indices in the frequency and time domain, respectively). In other words, one symbol on one sub-carrier is a resource element (RE). Each symbol comprises a number of sub-carriers in the frequency domain, depending on the channel bandwidth and configuration. The smallest time-frequency resource supported by the standard today is a set of plural sub-carriers and plural symbols (e.g., plural resource elements (RE)) and is called a resource block (RB). A resource block may comprise, for example, 84 resource elements, i.e., 12 subcarriers and 7 symbols, in case of normal cyclic prefix A mobile network used in wireless networks may be where the source and destination are interconnected by way of a plurality of nodes. In such a network, the source and destination may not be able to communicate with each other directly due to the distance between the source and destination being greater than the transmission range of the nodes. That is, a need exists for intermediate node(s) to relay communications and provide transmission of information. Accordingly, intermediate node(s) may be used to relay information signals in a relay network, having a network topology where the source and destination are interconnected by means of such intermediate nodes. In a hierarchical telecommunications network, the backhaul portion of the network may comprise the intermediate links between the core network and the small subnetworks of the entire hierarchical network. Integrated Access and Backhaul (IAB) Next generation NodeB use 5G New Radio communications such as transmitting and receiving NR User Plane (U-Plane) data traffic and NR Control Plane (C-Plane) data. Both, the UE and gNB may include addressable memory in electronic communication with a processor. In one embodiment, instructions may be stored in the memory and are executable to process received packets and/or transmit packets according to different protocols, for example, Medium Access Control (MAC) Protocol and/or Radio Link Control (RLC) Protocol.

In some aspects of the embodiments for handling of radio link failures in wireless relay networks, disclosed is a Mobile Termination (MT) functionality-typically provided by the User Equipment (UE) terminals-that may be implemented by Base Transceiver Stations (BTSs or BSs) nodes, for example, IAB nodes. In one embodiment, the MT functions may comprise common functions such as: radio transmission and reception, encoding and decoding, error detection and correction, signaling, and access to a SIM.

In a mobile network, an IAB child node may use the same initial access procedure (discovery) as an access UE to establish a connection with an IAB node/donor or parent-thereby attaching to the network or camping on a cell. In one embodiment, Radio Resource Control (RRC) protocol may be used for signaling between 5G radio network and UE, where RRC may have at least two states (e.g., RRC_IDLE and RRC_CONNECTED) and state transitions. The RRC sublayer may enable establishing of connections based on the broadcasted system information and may also include a security procedure. The U-Plane may comprise of PHY, MAC, RLC and PDCP layers.

Embodiments of the present system disclose methods and devices for an IAB-node to inform child nodes and/or UEs of upstream radio conditions and accordingly, the term IAB-node may be used to represent either a parent IAB-node or a child IAB-node, depending on where the IAB-node is in the network communication with the IAB-donor which is responsible for the physical connection with the core network. Embodiments are disclosed where an IAB-node (child IAB-node) may follow the same initial access procedure as a UE, including cell search, system information acquisition, and random access, in order to initially set up a connection to a parent IAB-node or an IAB-donor. That is, when an IAB base station (eNB/gNB) needs to establish a backhaul connection to, or camp on, a parent IAB-node or an IAB-donor, the IAB-node may perform the same procedures and steps as a UE, where the IAB-node may be treated as a UE but distinguished from a UE by the parent IAB-node or the IAB-donor.

In the disclosed embodiments for handling radio link failures in wireless relay networks, MT functionality-typically offered by a UE-may be implemented on an IAB-node. In some examples of the disclosed systems, methods, and device embodiments, consideration may be made in order for a child IAB-node to monitor a radio condition on a radio link to a parent IAB-node-where the parent IAB-node may itself be a child IAB-node in communication with an IAB-donor.

With reference to FIG. 1, the present embodiments include a mobile network infrastructure using 5G signals and 5G base stations (or cell stations). Depicted is a system diagram of a radio access network utilizing IAB nodes, where the radio access network may comprise, for example, one IAB-donor and multiple IAB-nodes. Different embodiments may comprise different number of IAB-donor and IAB-node ratios. Herein, the IAB nodes may be referred to as IAB relay nodes. The IAB-node may be a Radio Access Network (RAN) node that supports wireless access to UEs and wirelessly backhauls the access traffic. The IAB-donor may be a RAN node which may provide an interface to the core network to UEs and wireless backhauling functionality to IAB nodes. An IAB-node/donor may serve one or more IAB nodes using wireless backhaul links as well as UEs using wireless access links simultaneously. Accordingly, network backhaul traffic conditions may be implemented based on the wireless communication system to a plurality of IAB nodes and UEs.

With further reference to FIG. 1, a number of UEs are depicted as in communication with IAB nodes, for example, IAB nodes and IAB donor node, via wireless access link. Additionally, the IAB-nodes (child nodes) may be in communication with other IAB-nodes and/or an IAB-donor (all of which may be considered IAB parent nodes) via wireless backhaul link. For example, a UE may be connected to an IAB-node which itself may be connected to a parent IAB-node in communication with an IAB-donor, thereby extending the backhaul resources to allow for the transmission of backhaul traffic within the network and between parent and child for integrated access. The embodiments of the system provide for capabilities needed to use the broadcast channel for carrying information bit(s) (on the physical channels) and provide access to the core network.

FIG. 2 depicts an example of functional block diagrams for the IAB-donor and the IAB-node (see FIG. 1). The IAB-donor may comprise at least one Central Unit (CU) and at least one Distributed Unit (DU). The CU is a logical entity managing the DU collocated in the IAB-donor as well as the remote DUs resident in the IAB-nodes. The CU may also be an interface to the core network, behaving as a RAN base station (e.g., eNB or gNB). In some embodiments, the DU is a logical entity hosting a radio interface (backhaul/access) for other child IAB-nodes and/or UEs. In one configuration, under the control of CU, the DU may offer a physical layer and Layer-2 (L2) protocols (e.g., Medium Access Control (MAC), Radio Link Control (RLC), etc.) while the CU may manage upper layer protocols (such as Packet Data Convergence Protocol (PDCP), Radio Resource Control (RRC), etc.). An IAB-node may comprise DU and Mobile-Termination (MT) functions, where in some embodiments the DU may have the same functionality as the DU in the IAB-donor, whereas MT may be a UE-like function that terminates the radio interface layers. As an example, the MT may function to perform at least one of: radio transmission and reception, encoding and decoding, error detection and correction, signaling, and access to a SIM.

Embodiments include a mobile network infrastructure where a number of UEs are connected to a set of IAB-nodes and the IAB-nodes are in communication with each other for relay and/or an IAB-donor using the different aspects of the present embodiments. In some embodiments, the UE may communicate with the CU of the IAB-donor on the C-Plane using RRC protocol and in other embodiments, using Service Data Adaptation Protocol (SDAP) and/or Packet Data Convergence Protocol (PDCP) radio protocol architecture for data transport (U-Plane) through NR gNB. In some embodiments, the DU of the IAB-node may communicate with the CU of the IAB-donor using 5G radio network layer signaling protocol: F1 Application Protocol (F1-AP*) which is a wireless backhaul protocol that provides signaling services between the DU of an IAB-node and the CU of an IAB-donor. That is, as further described below, the protocol stack configuration may be interchangeable, and different mechanism may be used.

As illustrated by the diagram shown in FIG. 3, the protocols among the UE, IAB-nodes, and IAB donor are grouped into Control Plane (C-Plane) and User Plane (U-Plane). C-Plane carries control signals (signaling data), whereas the U-Plane carries user data. FIG. 3 shows an example of the embodiment where there are two IAB-nodes, IAB-node 1 and IAB-node 2, between the UE and the IAB-donor (two hops). Other embodiments may comprise a network with a single hop or multiple hops where there may be more than two IAB-nodes present.

FIG. 4 depicts a functional block diagram of an example protocol stack configuration for the U-Plane, the stack comprising Service Data Protocol (e.g., SDAP, 3GPP TS 38.324) which may carry user data (e.g., via IP packets). In one embodiment, the SDAP runs on top of PDCP (3GPP TS 38.323) and the L2/Physical layers. In one embodiment, an Adaptation Layer (e.g. Backhaul Adaptation Protocol, or BAP, 3GPP TS 38.340) is introduced between the IAB-node and the IAB-node/donor, where the Adaptation Layer carries relay-specific information, such as IAB-node/donor addresses, QoS information, UE identifiers, and potentially other information. In this embodiment, RLC (3GPP TS 38.322) may provide reliable transmission in a hop-by-hop manner while PDCP may perform end-to-end (UE-CU) error recovery. GTP-U (GPRS Tunneling Protocol User Plane) may be used for routing user data between CU and DU inside the IAB-donor.

FIG. 5A is a functional block diagram of an example protocol stack configuration for the C-Plane between an IAB-node (IAB-node 1) directly connected to the IAB-donor (via a single hop). In this embodiment, the MT component of IAB-node 1 may establish an RRC connection with the CU component of the IAB-donor. In parallel, RRC may be used for carrying another signaling protocol in order for CU/IAB-donor to control the DU component resident in the IAB-node 1. In one embodiment, such a signaling protocol may be referred to as F1 Application Protocol* (F1-AP*), either the protocol referred as F1-AP specified in 3GPP TS 38.473 or a protocol based on the F1-AP with potential extended features to accommodate wireless backhauls (the original F1-AP is designed for wirelines). In other embodiments, F1-AP may be used for CU-DU connection inside the IAB-donor. It is assumed that below RLC, MAC/PHY layers are shared with the U-Plane.

FIG. 5B depicts a functional block diagram of an example configuration of the C-Plane protocol stack for IAB-node 2, an IAB-node connected to the aforementioned IAB-node 1 (2 hops). In one embodiment, it may be assumed that the IAB-node 1 has already established RRC/F1-AP* connections with the IAB-donor as shown in FIG. 5A. In IAB-node 1 the signaling bearer for IAB-node 2 RRC/PDCP may be carried by the Adaptation Layer to the IAB-donor. Similar to FIG. 5A, the F1-AP* signaling is carried by the RRC of IAB-node 2.

FIG. 5C depicts yet another functional block diagram of an example configuration of the C-Plane protocol stack for UE's RRC signaling under the 2-hop relay configuration shown in FIG. 5B. Accordingly, the UE having an MT component and functionality, via the C-Plane, may be connected to the CU of the IAB-donor. Though traffic is routed through IAB-node 2 and IAB-node 1, as depicted, the two nodes are passive nodes in that the data is passed to the next node(s) without manipulation. That is, data is transmitted by the UE to the node it is connected to, e.g., IAB-node 2, and then IAB-node 2 transmits the data to the node that is connected to, e.g., IAB-node 1, and then IAB-node 1 transmits the data (without manipulation) to the IAB-donor.

FIGS. 5A, 5B, and 5C illustrate that the MT of each IAB-node or UE has its own end-to-end RRC connection with the CU of the IAB-donor. Likewise, the DU of each IAB-node has an end-to-end F1-APS' connection with the CU of the IAB-donor. Any IAB nodes present between such end points transparently convey RRC or F1-AP signaling traffic.

FIGS. 6A and 6B are diagrams of an example flow of information transmit/receive and/or processing by IAB-node(s) and an IAB-donor according to aspects of the present embodiments.

FIG. 6A depicts an example message sequence for IAB-node 1 to establish an RRC connection, followed by F1-AP* connection. It is assumed that IAB-node 1 has been pre-configured (or configured by the network) with information that instructs how to select a cell served by the IAB-donor. As shown in the figure, IAB-node 1-in an idle state (RRC_IDLE)-may initiate an RRC connection establishment procedure by sending Random Access Preamble to the IAB-donor, which may be received and processed by the DU of the IAB-donor. Upon successful reception of Random Access Response from the IAB-donor, IAB-node 1 may send a RRCSetupRequest, followed by reception of an RRCSetup and transmission of RRCSetupComplete. At this point of the message sequence, the IAB-node 1 may enter a connected state (RRC_CONNECTED) with the IAB-donor, and may proceed with a security procedure to configure encryption/integrity protection features. The CU of the IAB-donor may further send an RRCReconfiguration to IAB-node 1, which may comprise configuration parameters to configure radio bearers (e.g., data radio bearers (DRBs) and signaling radio bearers (SRBs)). In some embodiments, the RRCReconfiguration is sent to modify an RRC connection and establish Radio Connection between a UE and the network, however, in the present embodiment, the RRCReconfiguration may also be sent to configure a connection between an IAB-node and the network. RRC Connection Reconfiguration messages may be used to, for example, establish/modify/release Radio Bearers, and/or perform handover, etc. In one embodiment, any of the RRC messages transmitted from IAB-node 1 may include information identifying the IAB-node 1 as an IAB-node (not as a UE). For example, the Donor CU may be configured with a list of node identities (e.g., IMSI or S-TMSI) that may be allowed to use the service from the donor. The information may be used by the CU in the subsequence operations, for example, to distinguish a UE from an IAB-node.

As described above, following the RRC connection establishment procedure, the DU of IAB-node 1 and IAB-donor may proceed with F1 setup procedure using the F1-AP* protocol, which may activate one or more cells served by the DU of IAB-node 1—thereby allowing other IAB nodes and/or UEs to camp on the cell. In this procedure, the Adaptation Layer for IAB-node 1 and IAB—donor may be configured and activated as well.

FIG. 6B depicts an example message sequence or flow of information for IAB-node 2 to establish an RRC connection with IAB-donor, followed by the F1 setup procedure. It is assumed in this embodiment that IAB-node 1 has already performed the process disclosed in FIG. 6A to establish an RRC and F1-APS' connection. Referring back to FIG. 3, the IAB-node 2 shown in communication via the radio interface with IAB-node 1, may be also depicted in FIG. 6B as a child node of IAB-node 1 according to aspects of the present embodiments.

Due to the nature of wireless communications, the wireless backhaul links are susceptible to be deteriorated or broken at any time. In aspects of the present embodiments, the MT part of an IAB-node may constantly monitor the quality of the radio link and/or signal quality on the upstream of the IAB-node, where the radio link may be to a parent IAB node/donor of the IAB-node. If radio problems cannot be recovered in a designated duration, the MT may declare Radio Link Failure (RLF), meaning a loss of communication link may have occurred or signal strength is weak to continue (e.g., below a threshold).

FIG. 7 shows an example diagram of a scenario where an IAB-node (Node A) detects RLF on the upstream link to its parent node (Parent node 1). In some embodiments, the MT component of Node A may need to find another parent that is visible from the node. In this case, the MT component may perform a cell selection procedure, and if a suitable cell (Parent node 2) is successfully found, the Node A may then proceed with an RRC reestablishment procedure with the suitable cell (Parent node 2). It should be noted that Node A in this scenario needs to find a cell served by either an IAB-node or an IAB-donor (i.e., non-IAB-capable cells are not suitable). In one embodiment, a cell served by either an IAB-node or an IAB-donor may broadcast (e.g., in the system information, such as MIB, system information block type 1 (SIB1) or any of the other SIBs) a state, e.g., via a flag, as an indication indicating the IAB capability, which may further comprise an indication of the IAB functionality, a node type (IAB-node or IAB-donor), a hop count and/or the current state of the connectivity to the parent node. Alternatively, or in parallel, Node A may have been pre-configured or configured by the network with a list of IAB-capable cell identifications.

While Node A is trying to find a new suitable IAB-capable serving cell, the child IAB nodes (Child node 1 and Child node 2) and/or UEs (UE1 and UE2) may still be in connected mode with Node A. If Node A successfully recovers from the RLF before expiration of a pre-configured (or network-configured) period of time, the child nodes and/or the UEs may not be aware of the RLF. However, in the scenario where Node A fails or has failed to recover from the RLF in a timely manner (e.g., before expiration of a pre-configured/network-configured period of time), not only may these child nodes/UEs suffer discontinuity of service, but also all the nodes/UEs in the downstream may also suffer discontinuity of service.

The present embodiments disclose systems, methods, and device where an IAB-node may inform connected nodes (child nodes) or UEs, of the upstream radio conditions. In some embodiments, the upstream radio condition information may enable the child nodes or UEs to decide to stay connected with the IAB-node or to look for another node to connect to.

FIG. 8 shows an example scenario for Upstream RLF notification, a notification of an RLF, sent from a node (Node A) and detected on the node's upstream, to the child nodes and/or the directly connected UEs (also referred as Downstream notification of backhaul (BH) RLF in 3GPP TR 38.874). In one embodiment, upon receiving the notification, each of the child nodes and/or UEs may perform cell selection and, if successful, proceed to RRC reestablishment. As shown in FIG. 8, each of the child nodes and/or UEs, after a successful selection to a new node (Node B), may start the reestablishment procedure through Node B. That is, once a successful selection is made, the child nodes and/or UEs may transmit Random Access Preamble/Response messages, followed by RRCReestablishmentRequest and subsequent messages as illustrated in FIG. 8.

In one embodiment, Upstream RLF notification may be carried by the Adaptation Layer (e.g., a header part or a message body of the Adaptation Layer protocol). In an alternate embodiment, or in addition to, the notifications may be carried by the RLC sublayer, MAC, or a physical layer signaling (e.g., PDCCH). Additionally or alternatively, the notifications may be broadcasted via system information (e.g., MIB, SIB1 or any of the other SIBs) or transmitted in a dedicated manner.

Accordingly, in one embodiment, RRC resident in each of the child nodes and/or UEs may perform cell selection upon receiving a notification indicating the reception of the Upstream RLF notification from lower layers. In the present embodiments, this may be performed even if the radio link to the parent node remains in good condition. The node and/or UE may then start a timer, timer Txxx (e.g., T311 specified in 3GPP TS 38.331), based on the received notification, and upon selecting a suitable cell while timer Txxx is running, the node and/or UE may stop timer Txxx and initiate transmission of RRCReestablishmentRequest to the IAB-donor.

Once the RRC connection is reestablished, the CU of the IAB-donor may update the F1-AP* configurations in Node B as well as the child IAB-node that initiated the RRC reestablishment. In the scenario where the connecting device is a UE, F1-AP* configuration updates are not needed as they do not have the F1-AP* interface. Accordingly, the updated configuration from the IAB-donor may be used to reconfigure the routing topology which was modified or changed due to the RLF.

FIG. 9A shows another scenario where the child nodes and/or UEs may start a timer, for example, timer Tyyy, based on receiving an Upstream RLF notification. While the timer Tyyy is running, Node A may attempt to recover the upstream link by performing cell selection. In the scenario depicted in FIG. 9, Node A has successfully found a new parent node (Parent node 2) and may initiate the RRC reestablishment procedure. Node A, based on receiving F1-AP* configuration update from the CU of the IAB-donor, may transmit/send Upstream Recovery notification-a notification indicating that the upstream is recovered-to the child IAB-node and/or the UEs. If timer Tyyy has not expired yet, the child IAB-node and/or the UEs that receive the notification may stop timer Tyyy and stay connected with Node A. If the timer expires before receiving Upstream Recovery notification, the child IAB-node and/or the UEs may perform cell selection/RRC reestablishment as shown in FIG. 8. In one embodiment, the timer value/configuration may be pre-configured. In another embodiment, the timer value/configuration may be configured by the parent node (e.g., Parent node 1) via a dedicated signaling or via a broadcast signaling (e.g., system information, such as MIB, SIB1 or any of the other SIBs).

Similar to the previous scenario, in one embodiment, the Upstream RLF notification may be carried by the Adaptation Layer, RLC, MAC, or a physical layer signaling. Additionally, the notifications may be broadcasted via system information (e.g., MIB, SIB1 or any of the other SIBs) or transmitted in a dedicated manner.

In yet another embodiment for this scenario, RRC resident in each of the child nodes and/or UEs may start timer Tyyy upon receiving Upstream RLF notification from the lower layers. If the node and/or UE receive a notification indicating the reception of the Upstream RLF notification from lower layers while timer Tyyy is running, the node and/or UE may stop timer Tyyy. If timer Tyyy expires, the node and/or UE may then start timer Txxx and upon selecting a suitable cell while the timer is running, the node and/or UE may stop the timer and initiate transmission of RRCReestablishmentRequest.

FIG. 9B shows yet another scenario where Node A may start a timer Tzzz upon detecting an RLF. In this scenario, Node A may or may not send the aforementioned Upstream RLF notification to the child IAB-nodes and/or UEs. While the timer Tzzz is running, Node A may attempt to recover the upstream link by performing cell selection. In the scenario depicted in FIG. 9B, at the timer Tzzz expiry (cell selection failure), Node A may send a notification (e.g. Upstream Disconnect notification) to the child IAB-nodes/UEs notifying the unsuccessful RLF recovery. In this case, the child IAB-nodes/UEs that receive the notification may start the aforementioned timer Txxx and initiate the cell selection procedure as shown in FIG. 8. The notification may be carried by the Adaptation Layer, RLC, MAC, or a physical layer signaling, in a broadcast or a dedicated manner. In one embodiment, the timers Txxx and Tzzz may be the same timer or share same configurations. In another embodiment, the timers Txxx and Tzzz may be different timers or differently configured.

Additionally, notifications that an IAB-node provides to its downstream (children/UEs) may not be limited to RLF or RLF recovery. In some embodiments, the IAB-node may inform child nodes and/or UEs of the signal strength/quality (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ)), Received Signal Strength Indicator (RSSI), Signal to Interference plus Noise Ratio (SINR), error rates, a number of out-of-sync events, or any other types of measurements that indicate the radio condition of the upstream. In this case, IAB-nodes and/or UEs may be pre-configured or configured by the network with conditions for initiating cell selection/reestablishment. The notifications may be carried by the Adaptation Layer, RLC, MAC, or a physical layer signaling, in a broadcast or a dedicated manner.

In one embodiment, upon receiving one of the notifications from the parent node, the IAB-node and/or UE may send back or respond with an acknowledgement to the parent node, as shown in FIG. 8, FIGS. 9A and 9B.

FIG. 10 is a diagram illustrating an example of a radio protocol architecture for the control and user planes in a mobile communications network. The radio protocol architecture for the UE and/or the gNodeB may be shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. Layer 2 (L2 layer) is above the physical layer and responsible for the link between the UE and/or gNodeB over the physical layer. In the user plane, the L2 layer may include a media access control (MAC) sublayer, a radio link control (RLC) sublayer, and a packet data convergence protocol (PDCP) sublayer, which are terminated at the gNodeB on the network side. Although not shown, the UE may have several upper layers above the L2 layer including a network layer (e.g., IP layer) that is terminated at the PDN gateway on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.). The control plane also includes a radio resource control (RRC) sublayer in Layer 3 (L3 layer). The RRC sublayer is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the IAB-nodes and/or the UE and an IAB-donor.

Addressing Backhaul Conditions with Autonomous HANDOVER

FIG. 11 shows yet another example diagram of a telecommunications system 20 comprising wireless access node 22-1, also known as Donor node 1; wireless access node 22-2, also known as Donor node 2; IAB-node 24A, also known as Node A or relay node A; IAB-node 24B, also known as Node B or relay node B; and child node 1, also known as child node 30. The child node 30 may be, for example, a user equipment, UE, or an Integrated Access and Backhaul (IAB) node, as previously described. The wireless access node 22-1 and wireless access node 22-2 may be connected by a wired backhaul link 32. The other elements of FIG. 11 may be connected by wireless backhaul links, e.g., the wireless access node 22-1 may be connected by wireless backhaul link 34A to IAB-node 24A; the wireless access node 22-2 may be connected by wireless backhaul link 34B to IAB-node 24B; the IAB-node 24A may be connected by wireless backhaul link 36A to child node 30; and the IAB-node 24B may be connected by 36B to child node 30.

The example embodiments and modes of FIG. 11-FIG. 15 concern addressing problematic conditions on a wireless backhaul link using an autonomous handover. In general terms, the wireless access node 22-1 generates and sends to child node 30 a message which comprises information configured to facilitate a conditional handover of the wireless terminal. As used herein, the terms “handover” and “handoff” may be used interchangeably, and generally involve transfer of a connection or communication, at least partially, from one node or set of nodes to another node. Although the message may be of any appropriate type and bear any suitable name, in an example embodiment and mode described herein the message is a reconfiguration message and, for sake of illustration, is arbitrarily and not exclusively known, and shown in FIG. 11, as the conditional handover preparation message 40. The information comprising such message, e.g., the conditional handover preparation message 40, includes at least one identity of a target cell and one or more conditions which at least partially enable the wireless terminal to perform a conditional handover autonomously. In some configurations, the identity of a target cell may comprise one of or a combination of; a physical cell identity (PCI), CellIdentity (a cell identifier to unambiguously identify a cell within a PLMN), a PLMN-identity, a tracking area identity, and a RAN area code. As understood herein, the one or more conditions including a reception of a notification from the wireless relay node, e.g., from IAB-node 24A. Such notification is also known herein and shown in FIG. 11 as condition notification 42, and may be notification of a problematic condition on a wireless backhaul link. Upon reception of the condition notification 42, the child node 30 may perform an autonomous handover, depicted as event 44 in FIG. 11. The performance of the autonomous handover 44 is based on, e.g., enabled by using at least, the information provided in the conditional handover preparation message 40.

Various components and functionalities of the nodes shown in FIG. 11 are further shown in FIG. 12. FIG. 12 shows wireless access node 22-1 as comprising central unit 50-1 and distributed unit 52-1. The central unit 50-1 and distributed unit 52-1 may be realized by, e.g., be comprised of or include, one or more processor circuits, e.g., node processor(s) 54-1. The one or more node processor(s) 54-1 may be shared by central unit 50-1 and distributed unit 52-1, or each of central unit 50-1 and distributed unit 52-1 may comprise one or more node processor(s) 54-1. Moreover, central unit 50-1 and distributed unit 52-1 may be co-located at a same node site, or alternatively one or more distributed units 52-2 may be located at sites remote from central unit 50-1 and connected thereto by a packet network. The distributed unit 52-1 may comprise transceiver circuitry 56, which in turn may comprise transmitter circuitry 57 and receiver circuitry 58. The transceiver circuitry 56 includes antenna(e) for the wireless transmission. Transmitter circuitry 57 includes, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 58 comprises, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

As further shown in FIG. 12, node processor(s) 54-1 of wireless access node 22-1 may comprise message generator 60 and handover coordinator 62. The message generator 60 serves to generate, e.g., the conditional handover preparation message 40 as described herein. As mentioned above, the conditional handover preparation message 40 includes information comprising at least one identity of a target cell and one or more conditions for the wireless terminal performing the conditional handover autonomously. The handover coordinator 62 serves to communicate with the target cell, e.g., with another node which may be involved in the handover, so that suitable information and preparation can be obtained for the handover. In the example scenario described herein, the target cell will be a cell served by wireless access node 22-2.

As shown in FIG. 12 the IAB-node 24A, also known as wireless relay node 24A, in an example embodiment and mode comprises relay node mobile termination unit 70A and relay node distributed unit 72A. The relay node mobile termination unit 70A and relay node distributed unit 72A may be realized by, e.g., by comprised of or include, one or more processor circuits, e.g., relay node processor(s) 74A. The one or more relay node processor(s) 74A may be shared by relay node mobile termination unit 70A and relay node distributed unit 72A, or each of relay node mobile termination unit 70A and relay node distributed unit 72A may comprise one or more relay node processor(s) 74A. The relay node distributed unit 72A may comprise transceiver circuitry 76, which in turn may comprise transmitter circuitry 77 and receiver circuitry 78. The transceiver circuitry 76 includes antenna(e) for the wireless transmission. Transmitter circuitry 77 may include, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 78 may comprise, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

FIG. 12 further shows that IAB-node 24A may comprise radio condition detector 80 and notification generator 82. Both condition detector 80 and notification generator 82 may be realized or comprised by relay node processor(s) 74. The notification generator 82 serves to generate the condition notification 42, based on a condition detected by condition detector 80.

It should be understood that, although not illustrated in FIG. 12, the wireless access node 22-2 and IAB-node 24B of FIG. 11 and of FIG. 15 may have similar components and functionalities as the wireless access node 22-1 and IAB-node 24A, respectively, but with differently numbered/alphabetized suffixes denoting comparable components.

FIG. 12 shows child node 30 as comprising, in an example, non-limiting embodiment and mode, transceiver circuitry 86. The transceiver circuitry 86 in turn may comprise transmitter circuitry 87 and receiver circuitry 88. The transceiver circuitry 86 includes antenna(e) for the wireless transmission. Transmitter circuitry 87 may include, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 88 may comprise, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment. FIG. 12 further shows child node 30, which (as indicated before) may be a user equipment or Integrated Access and Backhaul (IAB) node, as also comprising node processor circuitry, e.g., one or more node processor(s) 90, and interfaces 92, including one or more user interfaces. Such user interfaces may serve for both user input and output operations, and may comprise (for example) a screen such as a touch screen that can both display information to the user and receive information entered by the user. The user interface 48 may also include other types of devices, such as a speaker, a microphone, or a haptic feedback device, for example.

In an example, non-limiting embodiment and mode shown in FIG. 12, the child node 30 may include frame/message generator/handler 94 and handover controller 96. As is understood by those skilled in the art, in some telecommunications system messages, signals, and/or data are communicated over a radio or air interface using one or more “resources”, e.g., “radio resource(s)”. The frame/message generator/handler 94 serves to handle messages, signals, and data received from other nodes, including but not limited to the conditional handover preparation message 40 and condition notification 42 described herein.

In a most basic example embodiment and mode, a wireless access node of the technology disclosed herein transmits a message which comprises information configured to facilitate a conditional handover of the wireless terminal, the information comprising at least one identity of a target cell and one or more conditions for the wireless terminal performing the conditional handover autonomously, the conditions including a reception of a notification from the wireless relay node. In a most basic example embodiment and mode of the technology disclosed herein, the wireless terminal, e.g., child node 30, receives such message.

Beyond the basic example embodiment and mode mentioned above, FIG. 13 shows further example, optional, non-limiting, basic acts or steps that may be performed by the wireless access node 22-1 of FIG. 11 and FIG. 12. Act 13-1 comprises initiating a handover coordination with another node upon occurrence of a predetermined event. In the example scenario described herein, the other node to be involved in the handover is wireless access node 22-2. The handover coordination of act 13-1 may be performed by handover coordinator 62, which works through a wired backhaul link interface to wireless access node 22-2. The predetermined event may be, for example, receipt of a measurement report from the wireless terminal, e.g., from child node 30, including a measurement regarding a signal received by the wireless terminal from another node, such as wireless access node 22-2. Act 13-2 comprises generating the conditional handover preparation message 40 to include the information facilitating the conditional handover 44. The conditional handover preparation message 40 may be generated, e.g., by message generator 60 of node processor(s) 54-1. Act 13-3 comprises sending or transmitting the conditional handover preparation message to child node 30, e.g., over the wireless backhaul links 34A and 36A and thus via IAB-node 24A.

Beyond the basic example embodiment and mode mentioned above, FIG. 14 shows further example, optional, non-limiting, basic acts or steps that may be performed by child node 30 of FIG. 11 and FIG. 12. Act 14-1 comprises receiving a message which comprises information configured to facilitate a conditional handover of the wireless terminal. Such message may be, for example, the conditional handover preparation message 40 described herein, which comprises at least one identity of a target cell and one or more conditions for the wireless terminal performing the conditional handover autonomously. Act 14-2 comprises receiving the condition notification 42 from an appropriate node, such as IAB-node 24A, which advises of the possible need of an autonomous handover. Act 14-3 comprises, upon receipt of the condition notification 42, performing an autonomous handover 44 to another node, e.g., to wireless access node 22-2 through IAB-node 24B.

In an example scenario shown in FIG. 11, IAB-node 22A, also known as Node A or wireless access node 22A, may detect a radio condition, such as a radio link failure, RLF, on the upstream link to its parent node, e.g. wireless access node 22-1 or Donor 1. In the example scenario of FIG. 11, the Child Node 30, which may be an IAB-node or an UE, was configured by the donor-node wireless access node 22-1 with a conditional handover, e.g., conditional handover preparation message 40 which may be a reconfiguration with sync, in advance, which allows the child node 30 to autonomously perform a handover to a designated cell, e.g., candidate target cell, when one or more conditions configured by the RRC of the Donor 1 are satisfied. In some configurations, the conditions may include reception of some of the aforementioned notifications from a parent node, such as Upstream RLF notification. When such conditions are met, the Child Node 1, e.g., child node 30, may start accessing the designated cell (e.g. Node B/Donor 2, also called IAB-node 24B/wireless access node 22-2) and perform a handover procedure. In one example embodiment and mode, the Donor nodes 1 and 2 may be physically collocated or even the same entity. In another example embodiment and mode, these two donor nodes, e.g., wireless access node 22-1 and wireless access node 22-2, may be separate nodes, mutually connected by a wired backhaul link (as shown in FIG. 11). It is assumed that prior to providing the configuration for the conditional handover to Child node 30, the two donor nodes wireless access node 22-1 and wireless access node 22-2 may perform negotiations/coordination with regard to the handover, e.g., act 11-3, described above. If the Donor node 1 and 2 are the same entity, the negotiations/coordination may be performed internally at the Donor node 1.

FIG. 15 depicts an example message flow for the scenario shown in FIG. 11. In the situation of FIG. 15, the child node 30 is in connected mode as shown by act 15-1. As act 15-3 the currently serving donor node, Donor 1 or wireless access node 22-1, may start a handover coordination with a node serving a potential target cell, e.g., a cell served by Donor 2 or wireless access node 22-2. The coordination of act 15-3 may comprise sharing of identifications of the Child Node 1, e.g., child node 30; security parameters; and radio link/resource configurations. As shown in FIG. 15, the coordination of act 15-3 may be triggered by act 15-2, e.g., receipt of a measurement report(s) transmitted by the Child Node 1, wherein the child node 30 reports sufficient signal quality observed from a cell served by the Node B, e.g., from IAB-node 24B.

After the coordination of act 15-3 is completed, as act 15-4 the Child Node 30 (in the RRC_CONNECTED state, as indicated by act 15-1) may receive the conditional handover preparation message 40. In an example embodiment and mode, the conditional handover preparation message 40 may be a RRCReconfiguration message comprising potential target cells, e.g. the cell served by Node B or IAB-node 24B, and one or more conditions for an autonomous handover. In the example flow of FIG. 15, the conditions may include a reception of the Upstream RLF notification. The other non-limiting examples of conditions may include or comprise signal quality thresholds for the downlink signals from the currently serving node, e.g., Node A=IAB-node 24A), as well as some of the other aforementioned notifications, such as Upstream Disconnect notification.

In the example flow shown in FIG. 15, as act 15-5 the Node A, e.g., IAB-node 24A, may detect an RLF on the upstream link, e.g., on wireless backhaul link 32. The condition on the wireless backhaul link 32 may be detected by the condition detector 80 of IAB-node 24A. The Node A may then send the Upstream RLF notification 42 to its child nodes/UEs, including the Child node 30. The condition notification 42 may be generated by notification generator 82. As optional act 15-7, Child node 30 may send back an acknowledgement. Moreover, due to the configured conditions, as act 15-8 the child node 30 may initiate a conditional handover to the configured target cell, e.g., in the example scenario, the cell served by IAB-node 24B, by performing a random access procedure. The random access procedure in which child node 30 participates comprises, as act 15-8, sending a Random Access Preamble message to IAB-node 24B and, as act 15-9, receiving a Random Access Response message from IAB-node 24B. Act 15-10 comprises the child node 30 sending a RRCReconfigurationComplete message to the donor of the target cell, e.g., Donor 2=wireless access node 22-2 via Node B=IAB-node 24B. As act 15-11 wireless access node 22-2 may use F1-AP* to update the routing configurations at the Node B for the Child Node 1, e.g., at IAB-node 24B for child node 30, and as act 15-12 may interact with wireless access node 22-1 to report the completion of the conditional handover. The wireless access node 22-1 may then release the resources saved for child node 30.

Accordingly, in the example embodiment and mode of FIG. 11-FIG. 15, an IAB-node or a UE may be configured with a conditional handover with conditions, comprising a reception of a notification representing the radio condition of the upstream radio link of the parent node and at least one identification of a target node. Upon receiving such a notification, the IAB-node or the UE may then perform an autonomous handover to the cell served by the target node.

Addressing Backhaul Conditions Involving Redundant Connections

FIG. 16 shows yet another example diagram of a telecommunications system 20 which, like the telecommunications system 20 of FIG. 15, comprises wireless access node 22-1, also known as Donor node 1; wireless access node 22-2, also known as Donor node 2; IAB-node 24A, also known as Node A or relay node A; IAB-node 24B, also known as Node B or relay node B; and child node 1, also known as child node 30. The child node 30 may be, for example, a user equipment, UE, or an Integrated Access and Backhaul (IAB) node, as previously described. The wireless access node 22-1 and wireless access node 22-2 may be connected by a wired backhaul link 32. The other elements of FIG. 16 may be connected by wireless backhaul links, e.g., the wireless access node 22-1 may be connected by wireless backhaul link 34A to IAB-node 24A; the wireless access node 22-2 may be connected by wireless backhaul link 34B to IAB-node 24B; the IAB-node 24A may be connected by wireless backhaul link 36A to child node 30; and the IAB-node 24B may be connected by 36B to child node 30.

The example embodiments and modes of FIG. 16-FIG. 20A, FIG. 20B concern addressing problematic conditions on a wireless backhaul link using redundant links. In general terms, the wireless access node 22-1 generates and sends to child node 30 at message which comprises information configured to activate plural signaling data path, such as first signaling data path SRB_f and second signaling data path SRB_s shown in FIG. 16. The first signaling data path SRB_f is established between wireless access node 22-1 and the wireless terminal also known as child node 30, and has its signaling data routed via wireless access node 22-1 and IAB-node 24A. In one configuration, the second signaling data path SRB_s may be established between wireless access node 22-2 and child node 30 and has its signaling data relayed by IAB-node 24B. In another configuration (not shown in FIG. 16), the second signaling data path SRB_s may be established directly established between wireless access node 22-2 and child node 30 without being relayed by an IAB-node. It should be noted that either of the first or second signaling data path may be a master signaling radio bearer, e.g., the signaling data bearer that is established first, and the other signaling data path may be a secondary signaling radio bearer that may be added after the master signaling radio bearer is established.

Although the message(s) configured to activate the plural signaling data paths may be of any appropriate type and bear any suitable name, in an example embodiment and mode described herein the message is a reconfiguration message and, for sake of illustration, is arbitrarily and not exclusively known, and shown in FIG. 16, as the plural path activation message 140. The plural path activation message 140 is received by the child node 30, after which both the first signaling data path SRB_f and the second signaling data path SRB_s are activated. Should the child node 30 thereafter receive a notification from the IAB-node 24A, the child node 30 may generate a report message (also referred as a failure information message) and transmit the message through the second signaling path SRB_s. The report message may include information based on the notification, and the notification may be based on a radio condition detected on the first signaling data path.

Various components and functionalities of the nodes shown in FIG. 16 are further shown in FIG. 17. Components of FIG. 17 which have similar names to the components of FIG. 12 also have comparable function. FIG. 17 shows wireless access node 22-1 as comprising central unit 50-1 and distributed unit 52-1. The central unit 50-1 and distributed unit 52-1 may be realized by, e.g., by comprised of or include one or more processor circuits, e.g., node processor(s) 54-1. The one or more node processor(s) 54-1 may be shared by central unit 50-1 and distributed unit 52-1 or each of central unit 50-1 and distributed unit 52-1 may comprise one or more node processor(s) 54-1. Moreover, central unit 50-1 and distributed unit 52-1 may be co-located at a same node site, or alternatively one or more distributed units 52-2 may be located at sites remote from central unit 50-1 and connected thereto by a packet network. The distributed unit 52-1 may comprise transceiver circuitry 56, which in turn may comprise transmitter circuitry 57 and receiver circuitry 58. The transceiver circuitry 56 includes antenna(e) for the wireless transmission. Transmitter circuitry 57 includes, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 58 comprises, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

As further shown in FIG. 17, node processor(s) 54-1 of wireless access node 22-1 may comprise message generator 60; plural path controller 162; and report handler 163. The message generator 60 serves to generate, e.g., plural path activation message 140 as described herein. The plural path controller 162 serves, e.g., to activate the plural paths, including first signaling data path SRB_f and second signaling data path SRB_s. The report handler 163 is configured to receive and process a report from child node 30 which is based on a notification representing a radio condition detected on one of the signaling data paths.

As shown in FIG. 17 the IAB-node 24A, also known as wireless relay node 24A, in an example embodiment and mode comprises relay mobile termination unit 70A and relay distributed unit 72A. The relay mobile termination unit 70A and relay distributed unit 72A may be realized by, e.g., by comprised of or include one or more processor circuits, e.g., relay node processor(s) 74A. The one or more relay node processor(s) 74A may be shared by relay mobile termination unit 70A and relay distributed unit 72A, or each of mobile termination unit 70A and distributed unit 72A may comprise one or more relay node processor(s) 74A. The relay node distributed unit 72A may comprise transceiver circuitry 76, which in turn may comprise transmitter circuitry 77 and receiver circuitry 78. The transceiver circuitry 76 includes antenna(e) for the wireless transmission. Transmitter circuitry 77 may include, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 78 may comprise, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

FIG. 17 further shows that IAB-node 24A may comprise radio condition detector 80 and notification generator 82. Both condition detector 80 and notification generator 82 may be realized or comprised by relay node processor(s) 74. The notification generator 82 serves to generate the condition notification 42, based on a condition detected by condition detector 80.

It should be understood that, although not illustrated in FIG. 17, the wireless access node 22-2 and IAB-node 24B of FIG. 16 and of FIG. 17 may have similar components and functionalities as the wireless access node 22-1 and IAB-node 24A, respectively, but with differently numbered/alphabetized suffixes denoting comparable components.

FIG. 17 shows child node 30 as comprising, in an example, non-limiting embodiment and mode, transceiver circuitry 86. The transceiver circuitry 86 in turn may comprise transmitter circuitry 87 and receiver circuitry 88. The transceiver circuitry 86 includes antenna(e) for the wireless transmission. Transmitter circuitry 87 may include, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 88 may comprise, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment. FIG. 17 further shows child node 30, which (as indicated before) may be a user equipment or Integrated Access and Backhaul (IAB) node, as also comprising node processor circuitry, e.g., one or more node processor(s) 90, and interfaces 92, including one or more user interfaces. Such user interfaces may serve for both user input and output operations, and may comprise (for example) a screen such as a touch screen that can both display information to the user and receive information entered by the user. The user interface 48 may also include other types of devices, such as a speaker, a microphone, or a haptic feedback device, for example.

In an example, non-limiting embodiment and mode shown in FIG. 17, the child node 30 may include frame/message generator/handler 94; path controller 196; and report generator 198. As is understood by those skilled in the art, in some telecommunications system messages, signals, and/or data are communicated over a radio or air interface using one or more “resources”, e.g., “radio resource(s)”. The frame/message generator/handler 94 serves to handle messages, signals, and data received from other nodes, including but not limited to incoming messages such as the plural path activation message 140 and condition notification 42 described herein, as well as outgoing messages such as a report message 199 generated by report generator 198. The path controller 196 works in conjunction with establishing, activating, and deactivating signaling data paths in which child node 30 participates, such as first signaling data path SRB_f and second signaling data path SRB_s.

In a most basic example embodiment and mode, a wireless access node of the technology disclosed herein transmits at least one message which activates a first signaling data path and a second signaling data path. The first signaling data path, e.g., first signaling data path SRB_f, and the second signaling data path, e.g., second signaling data path SRB_s, are both established between the wireless access node, e.g., wireless access node 22-1, and the wireless terminal, e.g., child node 30. Signaling data on the first signaling data path is relayed by a wireless relay node, e.g., IAB-node 24A. In a most basic example embodiment and mode of the technology disclosed herein, the wireless terminal, e.g., child node 30, receives such message. Further, the child node 30 may, as a condition on the first signaling data path SRB_f arises, processes a notification received from the wireless relay node and, upon reception of the notification, transmit a report message to the wireless access node on the second signaling data path. The report message comprises information based on the notification, and the notification is based on a radio condition detected on the first signaling data path.

Beyond the basic example embodiment and mode mentioned above, FIG. 18 shows further example, non-limiting, basic acts or steps that may be performed by the wireless access node 22-1 of FIG. 16 and FIG. 17. Act 18-1 comprises generating the at least one message, e.g., the message(s) being configured to activate a first signaling data path and a second signaling data path. As mentioned above, the first signaling data path and the second signaling data path are established between the wireless access node and the wireless terminal, and the signaling data on the second signaling data path is relayed by a wireless relay node. The message(s) of act 18-1, which may be termed as the plural path activation message(s) 140, may be generated by message generator 60. Act 18-2 comprises transmitting the at least one message(s), e.g., the plural path activation message 140, to the child node 30. The plural path activation message 140 may be transmitted by the transmitter circuitry 57 of wireless access node 22-1.

A problematic condition may thereafter arise, and for sake of example is illustrated herein as a radio link failure occurring on first signaling data path SRB_f. Act 18-3 comprises the wireless access node 22-1 receiving a report from child node 30, and in particular receiving a report message comprising information based on a notification received by child node 30. The notification is preferably based on a radio condition detected on the first signaling data path. Such notification may be the condition notification 42 described herein. The report message, e.g., report message 199, may be received by receiver circuitry 58 and handled by report handler 163. Act 18-4 comprises determining and/or performing an action based on the report message. An example of such an action for act 18-4 may be, for example, deactivating the first signaling data path SRB_f.

Beyond the basic example embodiment and mode mentioned above, FIG. 19 shows further example, non-limiting, basic acts or steps that may be performed by child node 30 of FIG. 16 and FIG. 17. Act 19-1 comprises receiving a message which activates a first signaling data path and a second signaling data path, e.g., the first signaling data path SRB_f and the second signaling data path SRB_s. Act 19-2 comprises receiving a notification of a condition detected on the first signaling data path SRB_f. The message of act 19-1 may be the plural path activation message 140 described herein, generated by wireless access node 22-1; the message of act 19-2 may be the condition notification 42 described herein, generated by IAB-node 24A. The messages of both act 19-1 and act 19-2 may be received through receiver circuitry 88 and processed by frame/message generator/handler 94. Act 19-3 comprises, upon reception of the notification of act 19-2, transmitting a report message to the wireless access node. The report message comprises information based on the notification; the notification is based on a radio condition detected on the first signaling data path.

In an example scenario shown in FIG. 16, child node 30, e.g., Child Node 1, which may be an IAB-node or a UE, establishes redundant connections (i.e. multiple connections or simultaneous connections, such as Dual Connectivity (DC)) for at least the signaling radio bearer (SRB) (and possibly the data radio bearers (DRBs) as well). In the scenario of FIG. 16, the SRB may be carried by two (or more) separate paths: (1) signaling data path SRB_f which includes wireless access node 22-1, IAB-node 24A, and child node 30, e.g., Donor 1—Node A—Child Node 1(SRB_f) and (2) signaling data path SRB_s which involves wireless access node 22-1, wireless access node 22-2, IAB-node 24B, and 30, e.g., Donor1—Donor2—Node B—Child Node 1(SRB_s). In one configuration, the wireless access node 22-1, e.g., Donor 1, may act as a master node while wireless access node 22-2, e.g., Donor 2, may behave as a secondary (or slave) node. In another configuration, the wireless access node 22-1, e.g., Donor 1, may act as a secondary (or slave) node while wireless access node 22-2, e.g., Donor 2, may behave as a master node. In one configuration, signaling data may duplicated and transmitted on the multiple paths, e.g., on first signaling data path SRB_f and second signaling data path SRB_s. In another configuration, packets for signaling data are split into the two paths, e.g., first signaling data path SRB_f and second signaling data path SRB_s, for increased throughput.

After establishing an RRC connection to wireless access node 22-1, e.g., to Donor 1, the Child Node 30 may be provisioned with a configuration with a secondary cell served by the wireless access node 22-2 and IAB-node 24B. Following the configuration, the Child Node 30 may use the multiple paths for transmitting/receiving signaling bearer (and possibly data bearers). In the present example embodiment and mode, at least one of the parent nodes of the Child node 30 may send some of the aforementioned notifications representing the radio condition of its upstream radio link. That is, either IAB-node 24A or IAB-node 24B may send such notifications, as and when the radio condition(s) occur. For example, similar to the previously disclosed embodiments, when detecting a radio link failure (RLF) on the upstream radio link of IAB-node 24A, the IAB-node 24A may send the Upstream RLF notification to its child nodes including the Child Node 30. In this case, the Child Node 30 may attempt to report this event to at least one of the serving donors using a path not affected by the RLF. In the scenario shown in the FIG. 16, the Child Node 30 may use the path SRB_s to send the report to the wireless access node 22-2 through the IAB-node 24B. In some example configurations, the report may be also conveyed to the wireless access node 22-1, e.g., to Donor 1, which may decide to reconfigure updated redundant connections to the Child Node 30.

FIG. 20A shows an example message flow for the scenario shown in FIG. 16, where the Child Node 30 may first establish an RRC connection with the Donor 1, which results in setting up the SRB_f. While the Child node 30 is in RRC_CONNECTED (depicted as act 20-1 in FIG. 20A), the wireless access node 22-1 may decide to configure an additional connection and, as represented by act 20-2, start a coordination with wireless access node 22-2. It should be noted that, similar to the previously disclosed embodiment, the wireless access node 22-1 and the wireless access node 22-2 may be physically collocated or separated entities, or even the same entity. As act 10-3 wireless access node 22-1 may send to the Child Node 30 RRCReconfiguration comprising a configuration to add a new SRB (SRB_s) and an identity of the cell to serve SRB_s, the identity of the cell served by IAB-node 24B. As act 20-4 Child Node 30 may then acknowledge to RRCReconfiguration by sending a RRCReconfigurationComplete message. As act 20-5 wireless access node 22-2 may use F1-APS' to update the routing configurations at the Node B, e.g., at IAB-node 24B, for the Child Node 30.

As act 20-6 the child node 30 may initiate a random access procedure by sending a Random Access Preamble message, and as act 20-7 may receive a Random Access Response message. The random access procedure of act 20-6 and act 207 serves to synchronize child node 30 to the IAB-node 24B.

Eventually, as act 20-8, IAB-node 24A may detect a specified radio condition on its upstream link. In the example scenario shown in FIG. 20A, the specified upstream condition may be a radio link failure (RLF), but could be other radio link condition(s) as well. Act 20-9 comprises IAB-node 24A sending a notification, e.g., condition notification 42, to child node 30. In the example scenario shown in FIG. 20A, in which the specified upstream condition may be a radio link failure (RLF), the condition notification 42 may be an Upstream RLF notification which may be sent to child nodes/UEs of IAB-node 24A, including but not necessarily limited to Child Node 30. As act 20-10 Child Node 30 may send back an acknowledgement of the condition notification 42 to IAB-node 24A. Further, upon receipt of the notification of act 20-9, e.g., upon receipt of condition notification 42, as act 20-11 the child node 30 may generate and transmit a report message reporting the RLF occurring on the path for SRB_f. The report message 199 may be generated by report generator 198 upon receipt of the condition notification 42.

In one example embodiment and mode shown in FIG. 20A, the report message of act 20-11 may be an RRC message of act 20-11 directed to the Donor 1, e.g., to wireless access node 22-1. As Act 20A-12, the Donor 2, e.g., wireless access node 22-2, may transfer the report message to the Donor 1 using an inter-node message on the wired backhaul link 32. Upon receipt of the report message, the Donor 1 may coordinate with the Donor 2 to deactivate the problematic signaling data path (e.g. the first signaling data path SRB_f), as shown in Act 20A-13. In one implementation, the wireless access node 22-1 aka Donor 1, now recognizing that SRB_f is torn down, may reconfigure the Child Node 30 with a new SRB configuration, e.g. releasing SRB_f. by sending another RRCReconfiguration. In parallel, wireless access node 22-1 may also use the F1-AP* to update the routing configuration of the Child Node 30, if the Child Node 30 is an IAB-node.

In another example embodiment and mode shown in FIG. 20B, the report message 42 of act 20B-11 is addressed to the parent node, e.g., IAB-node 24B using the Adaptation Layer, the RLC Layer, the MAC Layer or the physical layer signaling. Then, as act 20B-12, the parent node IAB-node 24B may convey the report message using a protocol, e.g., F1-AP*, to the Donor 2, e.g., to wireless access node 22-2. As act 20B-13 the wireless access node 22-2 may redirect the report message to the Donor 1, e.g., wireless access node 22-1, using an inter-node message on the wired backhaul link 32. Similar to the previous embodiment and mode shown in FIG. 20A, in one implementation, the wireless access node 22-1 aka Donor 1, now recognizing that SRB_f is torn down, may reconfigure the Child Node 30 with a new SRB configuration, e.g. releasing SRB_f. by sending another RRCReconfiguration. In parallel, wireless access node 22-1 may also use the F1-AP* to update the routing configuration of the Child Node 30, if the Child Node 30 is an IAB-node.

In either the example embodiment and mode of FIG. 20A or the example embodiment and mode of FIG. 20B, upon receipt of the report message 199 the wireless access node 22-1 may take appropriate action, such as for example, deactivating the first signaling data path SRB_f.

In one example embodiment and mode, the Child Node is preconfigured to send the report message upon receiving one of designated notifications from the parent node, e.g., from IAB-node 24A. In another example embodiment and mode, the Child Node is configured by an IAB-donor node to send the report message upon receiving one of designated notifications. In this latter case, RRCReconfiguration may be used to configure the designated notifications for sending report message.

Accordingly, in the example embodiment and mode of FIG. 16-FIG. 20A and FIG. 20B, an IAB-node or a UE configured with multiple radio paths for the signaling radio bearer(s) may receive from one parent node a notification representing the radio condition of the upstream radio link of one of the parent nodes. The IAB-node or the UE may use one or more other radio paths to send a report message reporting the radio condition to at least one IAB-donor node. The IAB-donor node that receives the report message may initiate reconfiguration for updated topology and/or routing of the relay network accordingly.

The system of IAB is expected to be reliable and robust against various kinds of possible failures. The technology disclosed herein thus provides methods and procedures to deal with a radio link failure on the backhaul link.

Conditional Handover Configurations in Wireless Relay Networks

FIG. 21 shows yet another example diagram of a telecommunications system 20 comprising wireless access node 22, IAB-node 24A, also known as wireless relay node 24A; target IAB node 24B; and child node 30. The child node 30 may be, for example, a user equipment, UE, or an Integrated Access and Backhaul (IAB) node, as previously described. For sake of simplification, node 30 may herein be referred to simply as IAB node 30 or wireless node 30. The telecommunications system 20 of FIG. 21 may also include other access nodes and backhaul connections as shown in FIG. 11, and the target IAB node 224B may be connected to such other access nodes or yet other IAB-nodes. Aspects of the wireless access node 22, wireless relay node 24A, and IAB node 30 are described in more detail with reference to FIG. 22.

In similar manner as FIG. 11, elements of FIG. 21 may be connected by wireless backhaul links, e.g., the wireless access node 22 may be connected by wireless backhaul link 34 to IAB-node 24; the IAB-node 24A may be connected by wireless backhaul link 36 to child node 30; and after a handover the target IAB-node 24B may be connected by link 33B to child node 30.

The example embodiments and modes of FIG. 21-FIG. 26 also concern addressing problematic conditions on a wireless backhaul link using an autonomous handover. In general terms, the wireless access node 22-1 generates and sends to child node 30 a message, in this example embodiment known as a conditional handover configuration message, which comprises information configured to facilitate a conditional handover of the wireless terminal. As used herein, the terms “handover” and “handoff” may be used interchangeably, and generally involve transfer of a connection or communication, at least partially, from one node or set of nodes to another node. Although the message may be of any appropriate type and bear any suitable name, in an example embodiment and mode described herein the message is a reconfiguration message and, for sake of illustration, is arbitrarily and not exclusively known, and shown in FIG. 21, as the conditional handover configuration message 40(21).

Various components and functionalities of the nodes shown in FIG. 21 are further shown in FIG. 22. FIG. 22 shows wireless access node 22 as comprising central unit 50 and distributed unit 52. The central unit 50 and distributed unit 52 may be realized by, e.g., be comprised of or include, one or more processor circuits, e.g., node processor(s) 54. The one or more node processor(s) 54 may be shared by central unit 50 and distributed unit 52, or each of central unit 50 and distributed unit 52 may comprise one or more node processor(s) 54. The transceiver circuitry 56 includes antenna(e) for the wireless transmission. Transmitter circuitry 57 includes, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 58 comprises, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

As further shown in FIG. 22, node processor(s) 54 of wireless access node 22 may comprise message generator 60(21) and handover coordinator 62. The message generator 60(21) serves to generate, e.g., the conditional handover configuration message 40(21) as described herein. As described in more detail, conditional handover configuration message 40(21) includes information comprising at least one identity of a target cell (also referred as a candidate target cell) and one or more conditions for the wireless terminal performing the conditional handover autonomously. The handover coordinator 62 serves to communicate with the target cell, e.g., with another node which may be involved in the handover, such as wireless relay node 24B, for example, so that suitable information and preparation can be obtained for the handover.

As mentioned above, the child node 30 may be a UE type wireless terminal or an IAB-node. For sake of representative discussion, FIG. 22 shows child node 30 in the form of an IAB-node, which could also itself be a relay node for other nodes. As shown in FIG. 22 the IAB node 30 comprises mobile termination unit 70 and distributed unit 72. The node mobile termination unit 70 and node distributed unit 72 may be realized by, e.g., by comprised of or include, one or more processor circuits, e.g., IAB node processor(s) 74. The one or more node processor(s) 74 may be shared by node mobile termination unit 70 and node distributed unit 72, or each of node mobile termination unit 70 and node distributed unit 72 may comprise one or more node processor(s) 74. The node distributed unit 72 may comprise transceiver circuitry 76, which in turn may comprise transmitter circuitry 77 and receiver circuitry 78. The transceiver circuitry 76 includes antenna(e) for the wireless transmission. Transmitter circuitry 77 may include, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 78 may comprise, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

FIG. 22 further shows that IAB-node 24A may comprise frame/message handler/generator 94(22) and handoff controller 96(22). The handoff controller 96(22) in turn comprises an evaluation unit or a comparison unit 97 which compares information 98 representing the triggering condition and information 99 representing the radio condition.

In an example embodiment and mode in which the child node 30 is a wireless terminal or user equipment rather than an IAB node, it will be appreciated that the handoff controller 96(22) with its evaluation unit or a comparison unit 97 may be provided in a wireless terminal processor such as understood with reference to FIG. 12.

The example embodiment of FIG. 21 discloses a detailed design of the conditional handover configuration for IAB-nodes. Herein, unless otherwise noted, operations and mode for “an MT part of an IAB-node” disclosed in the embodiments below also may apply to other suitable circuitry of an IAB node or of a wireless terminal, e.g., user equipment. In one configuration, the RRCReconfiguration message shown in FIG. 11 and as conditional handover configuration message 40(21) in FIG. 21 may comprise an information element CHOConfig, which may comprise a set of parameters to configure a conditional handover for an MT part of an IAB-node. In another configuration, another message, such as RRCCHOConfiguration, may be used to carry CHOConfig.

FIG. 23A shows a non-limiting example of the parameters that may be included in CHOConfig. Such parameters may include: Identification(s) of candidate target cell(s); Event(s) to trigger execution of CHO (e.g., conditional handover); RACH configuration(s) of the candidate target cell(s); uplink/downlink, UL/DL, configuration(s) of the candidate target cell(s); new UE identity(ies) (e.g. RNTI) to be used for the candidate target cell(s).

Listing 1 shows CHOConfig, an example format of an information element (IE) to be included in the message used for the CHO configuration.

Listing 1 CHOConfig ::= SEQUENCE {  CHOConfigToRemoveList CHOConfigToRemoveList OPTIONAL, -- Need N  CHOConfigToAddModList CHOConfigToAddModList OPTIONAL, -- Need N  } OPTIONAL, -- Need M CHOConfigToRemoveList ::= SEQUENCE (SIZE (1..maxNrofCHOConfigId) ) OF CHOConfigId ReportConfigToAddModList ::= SEQUENCE (SIZE (1..maxCHOConfigId) ) OF CHOConfigToAddMod CHOConfigToAddMod ::= SEQUENCE {  choConfigId CHOConfigId,  reportConfig CHOICE {   choConfigNR CHOConfigNR,   ...,   choConfigInterRAT choConfigInterRAT  } } CHOConfigNR ::= SEQUENCE {  CHOConditionList SEQUENCE (SIZE (1..maxCHOConditionList) ) OF CHOCondition } CHOCondition SEQUENCE {  candidateCellIDList SEQUENCE (SIZE (1..maxCandidateCellIDList) ) OF PhysCellId eventTriggered EventTriggerConfigCHO,   ...,   reportCGI ReportCGI  }  spCellConfigCommon ServingCellConfigCommon OPTIONAL, -- Need M  newUE-Identity RNTI-Value,  validity ENUMERATED {ms50, ms100, ms150, ms200, ms500, ms1000, ms2000, ms10000},  rach-ConfigDedicated CHOICE {   uplink RACH-ConfigDedicated,   supplementaryUplink RACH-ConfigDedicated  } OPTIONAL, -- Need N } EventTriggerConfigCHO::= SEQUENCE {  eventId CHOICE {   eventA1 SEQUENCE {    a1-Threshold MeasTriggerQuantity,   },   eventA2 SEQUENCE {    a2-Threshold MeasTriggerQuantity,   },   eventA3 SEQUENCE {    a3-Offset MeasTriggerQuantityOffset,   },   eventA4 SEQUENCE {    a4-Threshold MeasTriggerQuantity,   },   eventA5 SEQUENCE {    a5-Threshold1 MeasTriggerQuantity,    a5-Threshold2 MeasTriggerQuantity,   },   eventA6 SEQUENCE {    a6-Offset MeasTriggerQuantityOffset,   },   -...  }, MeasTriggerQuantity ::= CHOICE {  rsrp RSRP-Range,  rsrq RSRQ-Range,  sinr SINR-Range } MeasTriggerQuantityOffset ::= CHOICE {  rsrp INTEGER (−30..30),  rsrq INTEGER (−30..30),  sinr INTEGER (−30..30) } RSRP-Range ::= INTEGER(0..127) ...

In an example implementation, the events that triggers a conditional handover listed in Listing 1 are defined as follows:

-   -   Event A1: Serving becomes better than absolute threshold;     -   Event A2: Serving becomes worse than absolute threshold;     -   Event A3: Neighbour becomes amount of offset better than         PCell/PSCell;     -   Event A4: Neighbour becomes better than absolute threshold;     -   Event A5: PCell/PSCell becomes worse than absolute threshold1         AND Neighbour/SCell becomes better than another absolute         threshold2;     -   Event A6: Neighbour becomes amount of offset better than SCell.     -   Primary Cell (PCell): The Master Cell Group (MCG) cell,         operating on the primary frequency, in which the UE either         performs the initial connection establishment procedure or         initiates the connection re-establishment procedure.     -   Primary SCG (Secondary Cell Group) Cell (PSCell): For dual         connectivity operation, the SCG cell in which the UE performs         random access when performing the Reconfiguration with Sync         procedure.     -   Secondary Cell (SCell): For a UE configured with CA, a cell         providing additional radio resources on top of Special Cell

An IAB-node such as IAB node 30 of FIG. 21 and FIG. 22 may determine that a conditional handover is to occur by evaluating one or more measurement on one or more immediate upstream links relative to appropriate thresholds for the corresponding link(s). An “immediate” upstream link is a link over which the IAB node actually receives a radio communication from its immediate parent node, not a link between parents of the IAB node. For example, in the situation of FIG. 21, the immediate upstream link may be link 36A.

The measurements may correspond to certain radio condition “Events”, as described above. As described herein, the one or more Events that are to be evaluated, and the appropriate threshold(s) for each, may be communicated to the IAB node in a conditional handover configuration message 40(21). For example, if the evaluation of the measurement for the radio reception Event relative to the threshold indicates a link quality or condition that is inferior to what quality from another node or cell, the IAB node may autonomously execute a conditional handover. The foregoing describes the IAB-node 30 determining if a conditional handover should be performed based on measured quality of the immediate upstream link. However, there are other situations in which a conditional handover should also occur when a parent node, e.g., wireless relay node 24A, detects a problematic link between it and a node yet upstream from the parent node, such as a radio link failure indicated by RLF in FIG. 21. In such situation the IAB-node 30 may also need to perform a conditional handover. A failure that occurs somewhere in parent node's upstream can be known to the IAB node 30 only by a notification message 42(21) sent to the IAB-node from an upstream patent node. But to augment the conditional handover configuration message with additional cases which would cover the unfavourable radio condition encountered by the parent may undesirably complicate the conditional handover configuration message.

Therefore, in accordance with one aspect of the technology disclosed herein, to determine whether or not a triggering event is occurring (e.g., whether a triggering condition is met/satisfied), the IAB-node 20, e.g., the MT part 70 of the IAB-node 30 of FIG. 22, may treat or consider a notification message indicating parent node's upstream RLF event as if the RLF were occurring at the immediate upstream link for the IAB-node itself and thereby, as herein explained, facilitate possible conditional handover.

In order to do so the handover controller 96(22) of FIG. 22 is configured to make a determination of whether or not to execute a handover based on both the conditional handover configuration message and the notification received from the parent node. For example, the handover controller 96(22) of FIG. 22 may make the determination of whether or not to execute a handover based on both a triggering condition, received in the conditional handover configuration message, and the information representing the radio condition which is received in the notification from the wireless relay node. To this end, FIG. 22 shows handoff controller 96(22) as comprising an evaluation unit or a comparison unit 97 which compares information 98 representing the triggering condition and information 99 representing the radio condition.

In an example situation illustrated in FIG. 24A in which the IAB-node 30 itself detects a problem on one of its immediate upstream links, the comparison unit 97 compares a threshold comprising the information 98 representing the triggering condition 98 against the signal strength/quality of a signal on the immediate upstream link (wireless backhaul link 36) as measured by the IAB-node 30, e.g., the actually measured signal strength/quality is used as the information 99 representing the radio condition.

On the other hand, in an example scenario, illustrated in FIG. 24B, upon receiving the notification message 42(21), for sake of a comparison of a receive signal with a threshold in conjunction with the conditional handover determination, the IAB-node may consider that the received signal strength/quality (e.g. RSRP, RSRQ or SINR) of the serving cell, PCell, and/or PSCell as being equal or below a predetermined (or pre-configured) value (such as negative infinity). In this case, the predetermined/pre-configured value is compared with the threshold(s) of the triggering condition of concern. For example, when the IAB-node 30 receives the notification message 42(21) indicating an RLF, the IAB-node 30 behaves as if the signal strength/quality of the immediate upstream link were at or below the predetermined value. In other words, the information 99 representing the radio condition is presumed to be the predetermined value. Assuming that the predetermined value is low enough as compared to a threshold value comprising the information 98 representing the triggering condition, the handover controller 96(22) will trigger at least one configured triggering event.

The predetermined value which may be used by the comparison unit 97 for the received information 99 representing the radio condition may be configured at the IAB node, either pre-configured or configured by the network. For example, the predetermined value may be included in the conditional handover configuration message.

For example, assume that Event A3 is configured as a triggering event of a conditional handover to the MT part of the IAB-node. Upon receiving the notification message (e.g. Upstream RLF Notification), the MT part of the IAB-node, based on this embodiment, may consider that the A3 event is occurring (even if its immediate upstream link is not triggering the event). The MT part of the IAB-node may then execute the conditional handover as configured by CHOConfig.

As shown in FIG. 23B, the conditional handover configuration message may include plural triggering conditions, e.g., plural triggering events. The plural triggering events may include one or more of those listed above, such as Event A1, Event A2, Event A3, Event A4, Event A5 and Event A6. In this case, the predetermined/preconfigured value is compared with the threshold(s) of the triggering condition(s) of concern.

If the information 99 representing the radio condition is above the thresholds for all events indicated in the conditional handover configuration message, none of the conditions for the configured events will be met, and therefore the handoff controller 96(22) will not declare or determine a conditional handover. However, should the notification 42(21) be a radio link failure (RLF), and if the assumed predetermined value should be low enough, like negative infinity, the handoff controller 96(22) should determine the handover. If the notification indicates that the parent node is suffering from low signal strength/quality or an RLF, it may make sense for the IAB-node to execute HO, provided that the IAB-node is configured with conditional HO conditions with regard to signal strength/quality.

In an example implementation, when receiving the notification message, for an IAB node that has a MT part, the MT part of the IAB-node may consider that some of the triggering events, such as Event A2, A3 and A5 are automatically met. For example, if A2, A3, or A5 is configured as a triggering condition in the conditional handover configuration message, and if the information representing the radio condition is an RLF, the determination to execute a handover is made. If multiple triggering events are configured, the IAB-node may evaluate each of those. Once at least one of them is met, a HO is performed.

As shown in FIG. 23C, each triggering event may comprise a threshold value associate with the respective event, and optionally may also include an applicability indication as shown in FIG. 23D and FIG. 23E. As explained below, the applicability indication indicates whether or not the respective triggering condition may be applicable to the notification message 42(21).

As shown in FIG. 23D, the conditional handover configuration message, e.g., CHOConfig, may comprise at least one indication, e.g., an applicability indication, which serves to indicate whether or not the triggering condition(s) in CHOConfig is also applicable for the notifications with regard to an RLF on parent node's upstream link (not only to the immediate upstream link(s)). If the indication associated with a triggering event indicates that this triggering event is applicable to the notification message, the condition for the triggering event is evaluated with the information in the notification message. On the other hand, if the indication indicates that the condition is not applicable to the notification message, the IAB-node evaluates the condition based on its own measurement on the immediate upstream link(s) and does not use the notification for evaluating the condition. If the association indication is set to true, or present, the MT of the IAB-node may evaluate the triggering events in accordance with the configurations disclosed above in this embodiment. Otherwise, only the immediate upstream link(s) of the MT of the IAB-node may be used to evaluate the triggering event. The example implementation of FIG. 23D, wherein one applicability indication is commonly used for all of the triggering events, is also shown in Listing 2-1.

In another example configuration shown in FIG. 23E and Listing 2-2, one applicability indication is provided in the conditional handover configuration message for each triggering event (useForRLFNotification) may be used. For example, assume that A2 and A3 are configured for a conditional handover, and for A2 useForRLFNotification=false (or not present) and for A3 useForRLFNotification=true (or present). When the IAB-node detects A2 or A3 event on its immediate link based on measurements, it will trigger the conditional handover. But when the IAB-node receives the notification message with RLF, it will only evaluate A3. In the case of using a predetermined value, it is ensured that the target (=neighbor) cell becomes amount of offset better than PCell/PSCell (=serving), because the predetermined value is low, such as negative infinity.

Listing 2-1 CHOConfig ::= SEQUENCE {  CHOConfigToRemoveList CHOConfigToRemoveList OPTIONAL, -- Need N  CHOConfigToAddModList CHOConfigToAddModList OPTIONAL, -- Need N  } OPTIONAL, -- Need M CHOConfigToRemoveList ::= SEQUENCE (SIZE (1..maxNrofCHOConfigId) ) OF CHOConfigId ReportConfigToAddModList ::= SEQUENCE (SIZE (1..maxCHOConfigId) ) OF CHOConfigToAddMod CHOConfigToAddMod ::= SEQUENCE {  choConfigId CHOConfigId,  reportConfig CHOICE {   choConfigNR CHOConfigNR,   ...,   choConfigInterRAT choConfigInterRAT  }  useForRLFNotification BOOLEAN } ... Listing 2-2 EventTriggerConfigCHO::= SEQUENCE {  eventId CHOICE {   eventA1 SEQUENCE {    a1-Threshold MeasTriggerQuantity,   useForRLFNotification BOOLEAN   },   eventA2 SEQUENCE {    a2-Threshold MeasTriggerQuantity,   useForRLFNotification BOOLEAN   },   eventA3 SEQUENCE {    a3-Offset MeasTriggerQuantityOffset,   useForRLFNotification BOOLEAN   },   eventA4 SEQUENCE {    a4-Threshold MeasTriggerQuantity,   useForRLFNotification BOOLEAN   },   eventA5 SEQUENCE {    a5-Threshold1 MeasTriggerQuantity,    a5-Threshold2 MeasTriggerQuantity,   useForRLFNotification BOOLEAN   },   eventA6 SEQUENCE {    a6-Offset MeasTriggerQuantityOffset,   useForRLFNotification BOOLEAN   },   ...  }, ...

In yet another configuration, one indication per CHO configuration for one RAT (e.g. CHOConfigNR, CHOConfiglnterRAT) may be used.

Alternatively, the applicability indication described above (either a common or per triggering event) may indicate (i) applicable to both the immediate upstream link(s) and the notification message, (ii) applicable only to the immediate upstream link(s) or (iii) applicable only to the notification message. For example, for a given condition(s)

-   -   i. The condition(s) may be evaluated against measurement results         on its immediate upstream link(s), as well as against the         information in the notification.     -   ii. The condition(s) may be evaluated against measurement         results on its immediate upstream link(s), but not against the         information in the notification. For example, if the         notification indicates an RLF, it will not be evaluated and         therefore will not trigger a handover by itself.     -   iii. The condition(s) may be evaluated against the information         in the notification message. For example, even if the radio         condition measured at its immediate upstream link(s) becomes         bad, it will not cause a handover based on this condition(s).         This is mainly aimed for provisioning threshold(s) designated         for notification messages (e.g. two A2 events, one for         measurement and one for notification, with different         thresholds).

FIG. 24C shows another example scenario, which may be employed alternatively or additional with the example scenarios described above. In the example scenario of FIG. 24, the notification message 42(21) may carry signal quality/strength value(s)/indicator(s) measured by a parent node at the upstream link of the parent node. In other words, a parent node may provide a measurement of signal quality/strength value(s)/indicator(s) in the notification message 42(21). Upon reception of such measurement-bearing notification message, the MT of the IAB-node may use such value(s)/indicator(s) to evaluate the configured triggering events. That is, as shown in FIG. 24C, the information 99 representing the radio condition may comprise the measurement reported in the notification message, which may be compared by the handoff controller 96(22) with the threshold(s) of the information 98 representing the triggering condition. For example, in a case that Event A3 is configured with RSRP value (MeasTriggerQuantity=rsrp), upon receiving from its parent node the notification message including an RSRP value, the MT part of the IAB-node may use the RSRP value as if it were measured from the serving cell, PCell, or PSCell.

Thus, from the foregoing it can be seen that, an event, such as A1, A2, . . . , may be defined with a condition, such as a threshold. The IAB-node uses this condition to see if the event occurs. For example, if A2 is configured, the IAB-node compares (1) the measurement result (in the case of FIG. 24A), the signal strength/quality value included the notification message (in the case of FIG. 24C), and/or the predetermined value (in the case of FIG. 24B) with (2) the threshold, e.g., the information 98 representing the triggering condition. If the measurement result (or the value in the message) shows that it is below the threshold, A2 event occurs and a handover is triggered

Furthermore, CHOConfig, the conditional handover configuration, may comprise one or more trigger events designated for the notification message with regard to an RLF on parent node's upstream link. For example, Event Ax (e.g. A7) may be defined as a reception of the aforementioned Upstream RLF notification. Likewise, Event Ay (e.g. A8) may be defined as a reception of the aforementioned Upstream Disconnect notification. Listing 3 shows an example implementation of the configuration for such events, wherein Event A7 may be associated with a timer value for Tyyy.

Listing 3 EventTriggerConfigCHO::= SEQUENCE {  eventId CHOICE {   eventA1 SEQUENCE {    a1-Threshold MeasTriggerQuantity,   },   eventA2 SEQUENCE {    a2-Threshold MeasTriggerQuantity,   },   eventA3 SEQUENCE {    a3-Offset MeasTriggerQuantityOffset,   },   eventA4 SEQUENCE {    a4-Threshold MeasTriggerQuantity,   },   eventA5 SEQUENCE {    a5-Threshold1 MeasTriggerQuantity,    a5-Threshold2 MeasTriggerQuantity,   },   eventA6 SEQUENCE {    a6-Offset MeasTriggerQuantityOffset,   }  eventA7 SEQUENCE {   a7-timeToTrigger  }  eventA8 SEQUENCE {   ...  }  }, ...

Thus, in one configuration, a handover may be executed immediately after a configured triggering event(s) is evaluated. In another configuration, a final decision to execute the conditional handover may be made upon or after a timer (such as aforementioned Tyyy) expires, where the timer may be started upon receiving from its parent node a notification indicating an RLF (e.g. Upstream RLF Notification). The timer may stop (no handover executed) in a case that another notification indicating an RLF recovery (i.e. successful connection reestablishment) (e.g. Upstream Recovery notification) is received. The use of timers such as those mentioned above may be understood in conjunction with preceding example embodiments and modes, such as FIG. 8, FIG. 9A, and FIG. 9B, for example.

FIG. 25 illustrates generic, representative, basic acts or steps that may be performed by the wireless access node such as wireless access 22 of FIG. 21 and FIG. 22. Act 25-1 comprises generating a conditional handover configuration message comprising a triggering condition. Such conditional handover configuration message is illustrated as conditional handover configuration message 40(21) of FIG. 21, and may be generated by message generator 60(21) of FIG. 22. Act 25-2 comprises transmitting the conditional handover configuration message to the wireless node. As mentioned above, the notification message is sent by the wireless relay node to the wireless node, and includes information representing a radio condition detected on a path between the wireless relay node and the wireless access node. The triggering condition and the information representing the radio condition enable the wireless node to make a determination of whether or not the wireless node executes a handover.

FIG. 26 illustrates generic, representative, basic acts or steps that may be performed by the IAB node 30, the child node, of FIG. 21 and FIG. 22. Act 26-1 comprises receiving from the wireless access node a conditional handover configuration message comprising a triggering condition. Act 26-2 comprises receiving from the wireless relay node a first notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node. Act 26-3 comprises making a determination of whether or not to execute a handover based on the triggering condition and the information representing the radio condition.

The technology disclosed herein thus permits sharing of (1) a condition for a triggering event with the regular conditional HO based on measurements of the immediate link, and (2) the new conditional HO condition based on the information given by the notification message. If the predetermined/preconfigured value is not used, then there is no need to configure a condition designated for the new conditional HO.

Thus, the conditional handover configuration of the technology disclosed herein provides a condition(s) that the IAB-node can autonomously move to a candidate target cell. The condition is evaluated by the IAB-node, once it is given. In prior art, the condition is evaluated (compared) against signal quality measured on the (immediate) radio link. In various aspects of the technology disclosed herein, the condition may be also evaluated against the information provided by the notification message.

Failure Information in Wireless Relay Networks

FIG. 27-FIG. 31 show yet another example embodiment and mode of a telecommunications system 20. The telecommunications system 20 of FIG. 27-FIG. 31 provide configurations and contents for the aforementioned report message which reports a radio link failure, RLF, occurring on one of configured multiple paths (e.g. DC). The example embodiment and mode of FIG. 27-FIG. 31 may be applicable to and thus combinable with any other example embodiment and mode described herein. The report message, whether for the example embodiment and mode of FIG. 27 or for any other example embodiment and mode. may at times be referred as the FailureInformation message, and it may be also referred as the MCGFailureInformation message in a case that the RLF occurs on a Master Cell Group (MCG) path, or it may be referred to as the SCGFailureInformation message in a case that the RLF occurs on a Secondary Cell Group (SCG) path.

FIG. 27 and FIG. 28 particularly show wireless access node 22(27), which may be a donor access node; wireless relay node 24(27), and child node 30(27). The child node 30(27) may be, for example, a user equipment, UE, or an Integrated Access and Backhaul (IAB) node, as previously described. For sake of simplification, node 30(27) may herein be referred to simply as IAB node 30(27) or wireless node 30(27). The telecommunications system 20 of FIG. 27 may also include other access nodes and backhaul connections as shown in FIG. 11.

Various components and functionalities of the nodes shown in FIG. 27 are further shown in FIG. 28. FIG. 28 shows wireless access node 22(27) as comprising central unit 50 and distributed unit 52. The central unit 50 and distributed unit 52 may be realized by, e.g., be comprised of or include, one or more processor circuits, e.g., node processor(s) 54. The one or more node processor(s) 54 may be shared by central unit 50 and distributed unit 52, or each of central unit 50 and distributed unit 52 may comprise one or more node processor(s) 54. The transceiver circuitry 56 includes antenna(e) for the wireless transmission. Transmitter circuitry 57 includes, e.g., amplifier(s), modulation circuitry and other conventional transmission equipment. Receiver circuitry 58 comprises, e.g., amplifiers, demodulation circuitry, and other conventional receiver equipment.

As further shown in FIG. 28, node processor(s) 54 of wireless access node 22(27) may comprise message generator 60(27) and path activation controller 162(27). The message generator 60(27) serves to generate, e.g., one or more reconfiguration message(s) 200, shown as reconfiguration message 200 in FIG. 27. The reconfiguration message 200 serves to activate a first data path 202 and a second data path 204. As shown in FIG. 27, the first data path 202 is established between the wireless access node 22(27) and the wireless node 30(27); the second data path 204 is relayed by the wireless relay node 24(27). The message generator 60(27) may generate radio resource control, RRC, messages, such as a RRCReconfiguration message, and therefore may be included in or comprise an RRC entity of wireless access node 22(27).

The wireless relay node 24(27), in an example embodiment and mode comprises relay node mobile termination unit 70(27), relay node distributed unit 72(27), in similar manner as previously described IAB nodes. The relay node mobile termination unit 70(27) and relay node distributed unit 72(27) may be realized by, e.g., by comprised of or include, one or more processor circuits, e.g., relay node processor(s) 74(27). The one or more relay node processor(s) 74(27) may be shared by relay node mobile termination unit 70(27) and relay node distributed unit 72(27), or each of relay node mobile termination unit 70(27) and relay node distributed unit 72(27) may comprise one or more relay node processor(s) 74(27). The relay node distributed unit 72(27) may comprise transceiver circuitry 76, which in turn may comprise transmitter circuitry 77 and receiver circuitry 78, as understood with reference to previously described example embodiments and modes. The wireless relay node 24(27) may comprise radio condition detector 80 and notification generator 82(27). Both condition detector 80 and notification generator 82(27) may be realized or comprised by relay node processor(s) 74. The notification generator 82(27) serves to generate the radio link failure RLF notification message 42(27) shown in FIG. 27, which indicates a radio link failure (RLF) on the second data path 204.

The wireless node 30(27) may be a UE type wireless terminal or an IAB-node. For sake of representative discussion, FIG. 28 shows child node 30 in the form of a wireless terminal, although it should also be understood that the wireless node 30(27) may take the form of an IAB node such as IAB node 30 of FIG. 22, for example. Being shown as a wireless terminal, wireless node 30(27) includes, in an example, non-limiting embodiment and mode, transceiver circuitry 86(27). The transceiver circuitry 86(27) in turn may comprise transmitter circuitry 87 and receiver circuitry 88, as understood with reference to previously described embodiments and modes. The wireless node 30(27) also comprises node processor circuitry, e.g., one or more node processor(s) 90(27), and interfaces 92(97), including one or more user interfaces, as previously described with reference to other example embodiments and modes. Further, in an example, non-limiting embodiment and mode shown in FIG. 28, the child node 30 may include frame/message generator/handler 94(27) and handover controller 96(27). The wireless node 30(27) also comprises failure information message generator 210 which generates the failure information message 212 shown in FIG. 27. The failure information message generator 210 may comprise or be included in handover controller 96(27), or some other unit or functionality of node processor 90(27).

In the example embodiment and mode of FIG. 27 and FIG. 28, the wireless node 30(27) generates and sends the FailureInformation message 212 upon (1) detecting an RLF on one of the immediate upstream links for the multiple radio paths, or (2) receiving the RLF notification message 42(27). The RLF notification message 42(27) may be one of the aforementioned notification messages related to an RLF occurring on the upstream link of the parent node, e.g. Upstream RLF notification, Upstream Disconnect notification.

FIG. 29A—FIG. 29C illustrate various example contents or information elements of the failure information message 212 according to differing example implementations of the technology disclosed herein. The contents or information elements of FIG. 29A—FIG. 29C are not exhaustive, but serve merely to illustrate particular types of information of interest to the technology disclosed herein.

For example, FIG. 29A shows that the FailureInformation message may comprise an indication indicating whether this message is sent due to (1) or (2), e.g., whether (1) the failure information message 212 is sent upon the wireless node 30(27) itself detecting an RLF on one of the immediate upstream links for the multiple radio paths, or (2) the wireless node 30(27) receiving an RLF notification message 42(27) from another node such as wireless relay node 24(27). In the example implementation shown in FIG. 29A, this indication is implemented as FailureType, an information element (IE) in the FailureInformation message to indicate the type of the failure that causes transmission of the message.

Additionally or alternatively to the information element of the failure information message 212 shown in FIG. 29A, the wireless node 30(27) may use information received through the RLF notification message 42(27) received from wireless relay node 24(27) for generating the FailureInformation message. A first example of such use of the RLF notification message 42(27) to generate the failure information message 212 is understood with reference to FIG. 29B, wherein the FailureInformation message 212 is shown as including measurement data (e.g. signal quality/strength, such as RSRP, RSRQ, SINR, etc.) of the parent node's upstream link as obtained from the RLF notification message 42(27). A second example of such use of the RLF notification message 42(27) to generate the failure information message 212 is understood with reference to FIG. 29C, wherein the FailureInformation message 212 is shown as including node identifier(s) that detected radio link problems (e.g. RLF).

Listing 4 shows an example format of an example FailureInformation message.

Listing 4 FailureInformation ::= SEQUENCE {  criticalExtensions CHOICE {   c1 CHOICE {    FailureInformation  FailureInformation-IEs,    spare3 NULL, spare2 NULL, spare1 NULL   },   criticalExtensionsFuture SEQUENCE { }  } } FailureInformation-IEs ::= SEQUENCE {  failureReport FailureReport  OPTIONAL,  nonCriticalExtension SEQUENCE { } OPTIONAL } FailureReport ::= SEQUENCE {  failureType ENUMERATED {  t310-Expiry, randomAccessProblem,  rlc-MaxNumRetx,  scg-ChangeFailure, scg-reconfigFailure,  srb3-IntegrityFailure, BH_RLF},  measResultFregListNR-r15  MeasResultFregListFailNR-r15 OPTIONAL,  measResultSCG-r15 OCTET STRING OPTIONAL,  bhRLFDetectingNodeId  INTEGER{...}  OPTIONAL,  bhMeasResult  MeasQuantity  OPTIONAL,  . . . } MeasResultFregListFailNR-r15 ::= SEQUENCE (SIZE (1..maxFreqNR-r15) ) OF MeasResultFregFailNR-r15 MeasResultFregFailNR-r15 ::= SEQUENCE {  carrierFreq-r15  ARFCN-ValueNR-r15,  measResultCellList-r15  MeasResultCellListNR-r15 OPTIONAL,  . . . } MeasQuantity ::= CHOICE {  rsrp  RSRP-Range,  rsrq  RSRQ-Range,  sinr  SINR-Range }

It should be understood that, in some example configurations, the failure information message 212 may be generated by a failure information message generator 210 such as shown in FIG. 28 when the wireless node 30(27) is a wireless terminal. On the other hand, should the wireless node 30(27) take the form of an IAB node, the failure information message 212 may be generated by a similar failure information message generator in a mobile termination part of the IAB node.

FIG. 30 illustrates generic, representative, basic acts or steps that may be performed by the wireless access node such as wireless access node 22(27) of FIG. 27 and FIG. 28. Act 30-1 comprises generating at least one reconfiguration message. The at least one reconfiguration message, such as reconfiguration message 200 of FIG. 27, activates a first data path 202 and a second data path 204. The first data path 202 and the second data path 204 are established between the wireless access node and the wireless node, the second data path 204 being relayed by a wireless relay node such as wireless relay node 24(27). Act 30-2 comprises transmitting the at least one reconfiguration message. Act 30-3 comprises receiving, on the first data path, a failure information message which is based on a radio link failure notification message that the wireless node receives from the wireless relay node.

FIG. 31 illustrates generic, representative, basic acts or steps that may be performed by the wireless node 30(27) of FIG. 27 and FIG. 28. Act 31-1 comprises receiving from the wireless access node at least one reconfiguration message, such as reconfiguration message 200. The reconfiguration message 200 serves to activate the first data path 202 and the second data path 204. Act 31-2 comprises receiving from the wireless relay node a notification message indicating a radio link failure (RLF) on the second data path. Act 31-3 comprises transmitting a failure information message to the wireless access node using the first data path. As explained above, the failure information message may be based on the notification message and indicates the RLF occurring on the second data path.

The various example embodiments and modes described herein may, in some implementations, be utilized individually, while in other implementations one or more of the various example embodiments and modes may be combined so that features and advantages thereof may be cumulatively utilized.

The technology disclosed herein provides methods for handling cases where an IAB node loses the connection to the network due to a radio link failure. Example, non-limiting methods and features include:

-   -   The TAB node transmits to its child nodes/UEs information         representing the radio condition of its upstream link.     -   The child nodes/UEs decide, based on the received information,         whether or not to stay on the current serving TAB node or         reselect another cell/TAB node.     -   The child nodes/UEs may wait for a designated duration before         making the decision, expecting that the serving IAB node         recovers the upstream radio link during the duration.     -   The child nodes/UEs may be configured with a conditional         handover that allows an autonomous handover when its parent node         suffered from a designated radio condition on its upstream link.     -   The child nodes/UEs may be configured with multiple signaling         paths and may report a designated radio condition occurring on         one of the paths using one of the remaining paths.     -   The configuration for the conditional handover comprises a set         of triggering event(s), wherein the child nodes/UEs may use the         received information representing the radio condition of its         upstream link to evaluate the triggering event(s).     -   In the case that multiple paths are configured, the child         nodes/UEs may obtain information with regard to an RLF-related         event occurring on one of the multiple paths, and generate/send         a failure report including the information.

Certain units and functionalities of the systems 20 may be implemented by electronic machinery. For example, electronic machinery may refer to the processor circuitry described herein, such as node processor(s) 54, relay node processor(s) 74, and node processor(s) 90. Moreover, the term “processor circuitry” is not limited to mean one processor, but may include plural processors, with the plural processors operating at one or more sites. Moreover, as used herein the term “server” is not confined to one server unit, but may encompasses plural servers and/or other electronic equipment, and may be co-located at one site or distributed to different sites. With these understandings, FIG. 32 shows an example of electronic machinery, e.g., processor circuitry, as comprising one or more processors 290, program instruction memory 292; other memory 294 (e.g., RAM, cache, etc.); input/output interfaces 296 and 297, peripheral interfaces 298; support circuits 299; and busses 300 for communication between the aforementioned units. The processor(s) 290 may comprise the processor circuitries described herein, for example, node processor(s) 54, relay node processor(s) 74, and node processor(s) 90.

An memory or register described herein may be depicted by memory 294, or any computer-readable medium, may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, flash memory or any other form of digital storage, local or remote, and is preferably of non-volatile nature, as and such may comprise memory. The support circuits 299 are coupled to the processors 290 for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like.

Although the processes and methods of the disclosed embodiments may be discussed as being implemented as a software routine, some of the method steps that are disclosed therein may be performed in hardware as well as by a processor running software. As such, the embodiments may be implemented in software as executed upon a computer system, in hardware as an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware. The software routines of the disclosed embodiments are capable of being executed on any computer operating system, and is capable of being performed using any CPU architecture.

The functions of the various elements including functional blocks, including but not limited to those labeled or described as “computer”, “processor” or “controller”, may be provided through the use of hardware such as circuit hardware and/or hardware capable of executing software in the form of coded instructions stored on computer readable medium. Thus, such functions and illustrated functional blocks are to be understood as being either hardware-implemented and/or computer-implemented, and thus machine-implemented.

In terms of hardware implementation, the functional blocks may include or encompass, without limitation, digital signal processor (DSP) hardware, reduced instruction set processor, hardware (e.g., digital or analog) circuitry including but not limited to application specific integrated circuit(s) [ASIC], and/or field programmable gate array(s) (FPGA(s)), and (where appropriate) state machines capable of performing such functions.

In terms of computer implementation, a computer is generally understood to comprise one or more processors or one or more controllers, and the terms computer and processor and controller may be employed interchangeably herein. When provided by a computer or processor or controller, the functions may be provided by a single dedicated computer or processor or controller, by a single shared computer or processor or controller, or by a plurality of individual computers or processors or controllers, some of which may be shared or distributed. Moreover, use of the term “processor” or “controller” may also be construed to refer to other hardware capable of performing such functions and/or executing software, such as the example hardware recited above.

Nodes that communicate using the air interface also have suitable radio communications circuitry. Moreover, the technology disclosed herein may additionally be considered to be embodied entirely within any form of computer-readable memory, such as solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein.

Moreover, each functional block or various features of the wireless access ndoe 22, the wireless relay node 24, and/or the wireless terminal/wireless node 30 used in each of the aforementioned embodiments may be implemented or executed by circuitry, which is typically an integrated circuit or a plurality of integrated circuits. The circuitry designed to execute the functions described in the present specification may comprise a general-purpose processor, a digital signal processor (DSP), an application specific or general application integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic, or a discrete hardware component, or a combination thereof. The general-purpose processor may be a microprocessor, or alternatively, the processor may be a conventional processor, a controller, a microcontroller or a state machine. The general-purpose processor or each circuit described above may be configured by a digital circuit or may be configured by an analogue circuit. Further, when a technology of making into an integrated circuit superseding integrated circuits at the present time appears due to advancement of a semiconductor technology, the integrated circuit by this technology is also able to be used.

It will be appreciated that the technology disclosed herein is directed to solving radio communications-centric issues and is necessarily rooted in computer technology and overcomes problems specifically arising in radio communications. Moreover, the technology disclosed herein improves basic function of a radio access network, e.g., methods and procedures to deal with problematic conditions on a backhaul link, such as radio link failure (RLF), for example.

The technology disclosed herein encompasses one or more of the following nonlimiting, non-exclusive example embodiments and modes:

Example Embodiment 1: A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one wireless relay node, the wireless node comprising: receiver circuitry configured to: receive from the wireless access node a conditional handover configuration message comprising a triggering condition; receive from the wireless relay node a notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node; processor circuitry configured to make a determination of whether or not to execute a handover; wherein the determination of whether or not to execute a handover is based on the triggering condition and the information representing the radio condition.

Example Embodiment 2: The wireless node of Example Embodiment 1, wherein the triggering condition comprises at least one threshold value to be compared with signal strength/quality.

Example Embodiment 3: The wireless node of Example Embodiment 2, wherein the information representing the radio condition is a radio link failure (RLF), and a predetermined value of signal quality/strength is used to be compared with the at least one threshold value.

Example Embodiment 4: The wireless node of Example Embodiment 2, wherein the information representing the radio condition is one or more values of signal quality/strength to be compared with the at least one threshold value.

Example Embodiment 5: The wireless node of Example Embodiment 1, wherein the triggering condition is a reception of the notification message, the information representing a radio condition being an RLF.

Example Embodiment 6: The wireless node of Example Embodiment 1, wherein the triggering condition is associated with an applicability indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 7: The wireless node of Example Embodiment 6, wherein the conditional handover configuration message comprises plural triggering conditions, and wherein each of the plural triggering conditions comprises an applicability indication which indicates applicability of the respective triggering condition to the notification message.

Example Embodiment 8: The wireless node of Example Embodiment 1, wherein the determination of whether or not to execute a handover is made after a timer expires, the timer starting upon or after the notification message is received.

Example Embodiment 9: The wireless node of Example Embodiment 8, wherein the timer stops upon receiving a second notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, the information representing the radio condition indicating that an RLF is recovered.

Example Embodiment 10: The wireless node of Example Embodiment 8, wherein a duration of the timer is configured by the wireless access node.

Example Embodiment 11: A method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one wireless relay node, the method comprising: receiving from the wireless access node a conditional handover configuration message comprising a triggering condition; receiving from the wireless relay node a notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node; making a determination of whether or not to execute a handover; wherein the determination of whether or not to execute a handover is based on the triggering condition and the information representing the radio condition.

Example Embodiment 12: The method of Example Embodiment 11, wherein the triggering condition comprises at least one threshold value to be compared with signal strength/quality.

Example Embodiment 13: The method of Example Embodiment 12, wherein the information representing the radio condition is a radio link failure (RLF), and a predetermined value of signal quality/strength is used to be compared with the at least one threshold value.

Example Embodiment 14: The method of Example Embodiment 12, wherein the information representing the radio condition is one or more values of signal quality/strength to be compared with the at least one threshold value.

Example Embodiment 15: The method of Example Embodiment 11, wherein the triggering condition is a reception of the notification message, the information representing a radio condition being an RLF.

Example Embodiment 16: The method of Example Embodiment 11, wherein the triggering condition is associated with an indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 17: The method of Example Embodiment 16, wherein the conditional handover configuration message comprises plural triggering conditions, and wherein each of the plural triggering conditions comprises an applicability indication which indicates applicability of the respective triggering condition to the notification message.

Example Embodiment 18: The method of Example Embodiment 11, wherein the determination of whether or not to execute a handover is made after a timer expires, the timer starting upon or after the notification message is received.

Example Embodiment 19: The method of Example Embodiment 18, wherein the timer stops upon receiving a second notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, the information representing the radio condition indicating that an RLF is recovered.

Example Embodiment 20: The method of Example Embodiment 18, wherein a duration of the timer is configured by the wireless access node.

Example Embodiment 21: A wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through at least one wireless relay node, the wireless access node comprising: processor circuitry configured to generate a conditional handover configuration message comprising a triggering condition; transmitter circuitry configured to transmit the conditional handover configuration message to the wireless node; wherein a notification message is sent by the wireless relay node to the wireless node, the notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, and; the triggering condition and the information representing the radio condition enable the wireless node to make a determination of whether or not the wireless node executes a handover.

Example Embodiment 22: The wireless access node of Example Embodiment 21, wherein the triggering condition comprises at least one threshold value to be compared with signal strength/quality.

Example Embodiment 23: The wireless access node of Example Embodiment 22, wherein the information representing the radio condition is a radio link failure (RLF), and a pre-determined value of signal quality/strength is used to be compared with the at least one threshold value.

Example Embodiment 24: The wireless access node of Example Embodiment 22, wherein the information representing the radio condition is one or more values of signal quality/strength to be compared with the at least one threshold value.

Example Embodiment 25: The wireless access node of Example Embodiment 21, wherein the triggering condition is a reception of the notification message, the information representing a radio condition being an RLF.

Example Embodiment 26: The wireless access node of Example Embodiment 21, wherein the triggering condition is associated with an indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 27: The wireless access node of Example Embodiment 26, wherein the conditional handover configuration message comprises plural triggering conditions, and wherein each of the plural triggering conditions comprises an applicability indication which indicates applicability of the respective triggering condition to the notification message.

Example Embodiment 28: The wireless access node of Example Embodiment 21, wherein the determination of whether or not to execute a handover is made after a timer expires, the timer starting upon or after the notification message is received.

Example Embodiment 29: The wireless access node of Example Embodiment 28, wherein the timer stops upon the wireless node receiving a second notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, the information representing the radio condition indicating that an RLF is recovered.

Example Embodiment 30: The wireless access node of Example Embodiment 28, wherein a duration of the timer is configured to the wireless node by the wireless access node.

Example Embodiment 31: A method for a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through at least one wireless relay node, the method comprising: generating a conditional handover configuration message comprising a triggering condition; transmitting the conditional handover configuration message to the wireless node; wherein: a notification message is sent by the wireless relay node to the wireless node, the notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, and; the triggering condition and the information representing the radio condition enable the wireless node to make a determination of whether or not the wireless node executes a handover.

Example Embodiment 32: The method of Example Embodiment 31, wherein the triggering condition comprises at least one threshold value to be compared with signal strength/quality.

Example Embodiment 33: The method of Example Embodiment 32, wherein the information representing the radio condition is a radio link failure (RLF), and a predetermined value of signal quality/strength is used to be compared with the at least one threshold value.

Example Embodiment 34: The method of Example Embodiment 32, wherein the information representing the radio condition is one or more values of signal quality/strength to be compared with the at least one threshold value.

Example Embodiment 35: The method of Example Embodiment 31, wherein the triggering condition is a reception of the notification message, the information representing a radio condition being an RLF.

Example Embodiment 36: The method of Example Embodiment 31, wherein the triggering condition is associated with an indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 37: The wireless access node of Example Embodiment 36, wherein the conditional handover configuration message comprises plural triggering conditions, and wherein each of the plural triggering conditions comprises an applicability indication which indicates applicability of the respective triggering condition to the notification message.

Example Embodiment 38: The method of Example Embodiment 31, wherein the determination of whether or not to execute a handover is made after a timer expires, the timer starting upon or after the notification message is received.

Example Embodiment 39: The method of Example Embodiment 38, wherein the timer stops upon the wireless node receiving a second notification message including information representing a radio condition detected on a path between the wireless relay node and the wireless access node, the information representing the radio condition indicating that an RLF is recovered.

Example Embodiment 40: The method of Example Embodiment 38, wherein a duration of the timer is configured to the wireless node by the wireless access node.

Example Embodiment 41: A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN), the wireless node comprising: receiver circuitry configured to: receive from the wireless access node at least one reconfiguration message, the reconfiguration message activating a first data path and a second data path, the first data path and the second data path being established between the wireless access node and the wireless node, the second data path being relayed by a wireless relay node, and; receive from the wireless relay node a notification message indicating a radio link failure (RLF) on the second data path; processor circuitry configured to generate a failure information message; transmitter circuitry configured to transmit the failure information message to the wireless access node using the first data path; wherein the failure information message is based on the notification message and indicates the RLF occurring on the second data path.

Example Embodiment 42: The wireless node of Example Embodiment 41, wherein the failure information message includes a type of failure, the type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 43: The wireless node of Example Embodiment 41, wherein the notification message includes location information identifying a node on the second data path that detect the RLF, and the failure information message includes the location information.

Example Embodiment 44: The wireless node of Example Embodiment 41, wherein the notification message includes one or more measurement values of signal strength/quality, and the failure information message includes the one or more measurement values.

Example Embodiment 45: A method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN), the method comprising: receiving from the wireless access node at least one reconfiguration message, the reconfiguration message activating a first data path and a second data path, the first data path and the second data path being established between the wireless access node and the wireless node, the second data path being relayed by a wireless relay node, and; receiving from the wireless relay node a notification message indicating a radio link failure (RLF) on the second data path; generating a failure information message; transmitting the failure information message to the wireless access node using the first data path; wherein the failure information message is based on the notification message and indicates the RLF occurring on the second data path.

Example Embodiment 46: The method of Example Embodiment 45, wherein the failure information message includes a type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 47: The method of Example Embodiment 45, wherein the notification message includes location information identifying a node on the second data path that detect the RLF, and the failure information message includes the location information.

Example Embodiment 48: The method of Example Embodiment 45, wherein the notification message includes one or more measurement values of signal strength/quality, and the failure information message includes the one or more measurement values.

Example Embodiment 49: A wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node, the wireless access node comprising: processor circuitry configured to generate at least one reconfiguration message, the at least one reconfiguration message activating a first data path and a second data path, the first data path and the second data path being established between the wireless access node and the wireless node, the second data path being relayed by a wireless relay node; transmitter circuitry configured to transmit the at least one reconfiguration message; receiver circuitry configured to receive a failure information message on the first data path; wherein the failure information message is based on a notification message that the wireless node receives from the wireless relay node, the notification message indicating a radio link failure (RLF) on the second data path.

Example Embodiment 50: The wireless access node of Example Embodiment 49, wherein the failure information message includes a type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 51: The wireless access node of Example Embodiment 49, wherein the notification message includes location information identifying a node on the second data path that detect the RLF, and the failure information message includes the location information.

Example Embodiment 52: The wireless access node of Example Embodiment 49, wherein the notification message includes one or more measurement values of signal strength/quality, and the failure information message includes the one or more measurement values.

Example Embodiment 53: A method for a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node, the method comprising: generating at least one reconfiguration message, the at least one reconfiguration message activating a first data path and a second data path, the first data path and the second data path being established between the wireless access node and the wireless node, the second data path being relayed by a wireless relay node; transmitting the at least one reconfiguration message; receiving a failure information message on the first data path; wherein the failure information message is based on a notification message that the wireless node receives from the wireless relay node, the notification message indicating a radio link failure (RLF) on the second data path.

Example Embodiment 54: The method of Example Embodiment 53, wherein the failure information message includes a type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 55: The method of Example Embodiment 54, wherein the notification message includes location information identifying a node on the second data path that detect the RLF, and the failure information message includes the location information.

Example Embodiment 56: The method of Example Embodiment 53, wherein the notification message includes one or more measurement values of signal strength/quality, and the failure information message includes the one or more measurement values.

Example Embodiment 57: A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through an Integrated Access and Backhaul (IAB) node, the wireless node comprising: receiver circuitry configured to: receive from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; receive from the IAB node a notification message comprising information representing a radio condition measured on a path between the IAB node and the wireless access node, and; processor circuitry configured to perform, based on the triggering condition and the information, a handover using the configuration of the candidate target cell.

Example Embodiment 58: The wireless node of Example Embodiment 57, wherein the information corresponds to signal strength/quality, and the handover is performed by evaluating the signal strength/quality and/or the at least one threshold value.

Example Embodiment 59: The wireless node of Example Embodiment 57, wherein the information corresponds to a radio link failure (RLF), and the handover is performed by evaluating a pre-determined value of signal quality/strength and/or the at least one threshold value.

Example Embodiment 60: The wireless node Example Embodiment 57, wherein the triggering condition further comprises an applicability indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 61: A method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one Integrated Access and Backhaul (IAB) node, the method comprising: receiving from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell; receiving from the IAB node a notification message, and; making a determination of whether or not to execute a handover using the conditional handover configuration; wherein the triggering condition comprises at least one threshold value; the notification message comprises information representing a radio condition detected on a path between the wireless relay node and the wireless access node, and; the determination is based on the at least one threshold value and the information.

Example Embodiment 61: The method of Example Embodiment 60, wherein the information corresponds to signal strength/quality, and the determination is performed by comparing the signal strength/quality and the at least one threshold value.

Example Embodiment 62: The method of Example Embodiment 60, wherein the information corresponds to a radio link failure (RLF), and the determination is performed by comparing a pre-determined value of signal quality/strength and the at least one threshold value.

Example Embodiment 63: The method of Example Embodiment 60, wherein the triggering condition further comprises an applicability indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 64: A wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through an Integrated Access and Backhaul (IAB) node, the wireless access node comprising:

processor circuitry configured to generate a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; transmitter circuitry configured to transmit the reconfiguration message to the wireless node; wherein the triggering condition and information are used by the wireless node to perform a handover using the configuration of the candidate target cell, the information representing a radio condition measured on a path between the IAB node and the wireless access node, and; the information is included in a notification message sent to the wireless node by the IAB node.

Example Embodiment 65: The wireless access node of Example Embodiment 64, wherein the information corresponds to signal strength/quality, and the handover is performed by evaluating the signal strength/quality and/or the at least one threshold value.

Example Embodiment 66: The wireless access node of Example Embodiment 64, wherein the information corresponds to a radio link failure (RLF), and the determination is performed by evaluating a pre-determined value of signal quality/strength and/or the at least one threshold value.

Example Embodiment 67: The wireless access node of Example Embodiment 64, wherein the triggering condition further comprises an applicability indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 68: A method for a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through an Integrated Access and Backhaul (IAB) node, the method comprising: generating a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising a triggering condition and a configuration of a candidate target cell, the triggering condition comprising at least one threshold value; transmitting the reconfiguration message to the wireless node; wherein: the triggering condition and information are used by the wireless node to perform a handover using the configuration of the candidate target cell, the information representing a radio condition measured on a path between the IAB node and the wireless access node, and; the information is included in a notification message sent to the wireless node by the IAB node.

Example Embodiment 69: The method of Example Embodiment 68, wherein the information corresponds to signal strength/quality, and the handover is performed by evaluating the signal strength/quality and/or the at least one threshold value.

Example Embodiment 70: The method of Example Embodiment 68, wherein the information corresponds to a radio link failure (RLF), and the determination is performed by evaluating a pre-determined value of signal quality/strength and/or the at least one threshold value.

Example Embodiment 71: The method of Example Embodiment 68, wherein the triggering condition further comprises an applicability indication indicating whether or not the triggering condition is applicable to the notification message.

Example Embodiment 72: A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN), the wireless node comprising: processor circuitry configured to establish, with the radio access node, dual connectivity (DC) comprising a first connection and a second connection, the first connection being relayed by an Integrated Access and Backhaul (IAB) node; receiver circuitry configured to receive from the IAB node a notification message indicating a radio link failure (RLF) on the first connection, and; transmitter circuitry configured to transmit, based on the notification message, a failure information message to the wireless access node using the second connection, wherein; the failure information message comprises information representing the RLF.

Example Embodiment 73: The wireless node of Example Embodiment 72, wherein the information representing the RLF comprises a type of failure, the type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 74: The wireless node of Example Embodiment 72, wherein the notification message comprises information identifying a node on the first connection that detects the RLF, and the information representing the RLF comprises the information identifying the node.

Example Embodiment 75: The wireless node of Example Embodiment 72, wherein the notification message comprises one or more measurement values of signal strength/quality, and the information representing the RLF comprises the one or more measurement values.

Example Embodiment 76: A method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN), the method comprising: establishing, with the radio access node, dual connectivity (DC) comprising a first connection and a second connection, the first connection being relayed by an Integrated Access and Backhaul (IAB) node; receiving from the IAB node a notification message indicating a radio link failure (RLF) on the first connection; transmitting, based on the notification message, a failure information message to the wireless access node using the second connection; wherein the failure information message comprises information representing the RLF

Example Embodiment 77: The method of Example Embodiment 76, wherein the information representing the RLF comprises a type of failure, the type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 78: The method of Example Embodiment 76, wherein the notification message comprises information identifying a node on the first connection that detects the RLF, and the information representing the RLF comprises the information identifying the node.

Example Embodiment 79: The method of Example Embodiment 76, wherein the notification message comprises one or more measurement values of signal strength/quality, and the information representing the RLF comprises the one or more measurement values.

Example Embodiment 80: A wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node, the wireless access node comprising: processor circuitry configured to establish, with the wireless node, dual connectivity (DC) comprising a first connection and a second connection, the first connection being relayed by an Integrated Access and Backhaul (IAB) node, and; receiver circuitry configured to receive, on the second connection, a failure information message; wherein the failure information message is based on a notification message that the wireless node receives from the IAB node, the notification message indicating a radio link failure (RLF) on the first connection, and; the failure information message comprises information representing the RLF.

Example Embodiment 81: The wireless access node of Example Embodiment 80, wherein the information representing the RLF comprises a type of failure, the type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 82: The wireless access node of Example Embodiment 80, wherein the notification message comprises information identifying a node on the first connection that detects the RLF, and the information representing the RLF comprises the information identifying the node.

Example Embodiment 83: The wireless access node of Example Embodiment 80, wherein the notification message comprises one or more measurement values of signal strength/quality, and the information representing the RLF comprises the one or more measurement values.

Example Embodiment 84: A method for a wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node, the method comprising: establishing, with the wireless node, dual connectivity (DC) comprising a first connection and a second connection, the first connection being relayed by an Integrated Access and Backhaul (IAB) node, and; receiving, on the second connection, a failure information message; wherein the failure information message is based on a notification message that the wireless node receives from the wireless relay node, the notification message indicating a radio link failure (RLF) on the first connection, and; the failure information message comprises information representing the RLF.

Example Embodiment 85: The method of Example Embodiment 84, wherein the information representing the RLF comprises a type of failure indicating whether or not the transmission of the failure information message is caused by the notification message.

Example Embodiment 86: The method of Example Embodiment 84, wherein the notification message comprises information identifying a node on the first connection that detects the RLF, and the information representing the RLF comprises the location information identifying the node.

Example Embodiment 87: The method of Example Embodiment 84, wherein the notification message comprises one or more measurement values of signal strength/quality, and the information representing the RLF comprises the one or more measurement values.

One or more of the following documents may be pertinent to the technology disclosed herein (all of which are incorporated herein by reference in their entirety):

R2-1903583 BH RLF recovery for IAB Qualcomm Inc R2-1903684 Configuration of BH RLC CH Samsung R2-1903685 Overview on control signaling transmission in IAB Samsung R2-1903698 On topology adaptation upon backhaul-link-failure recovery ASUSTeK R2-1903730 Further consideration of topology adaptation upon BH RLF Kyocera R2-1903928 Allowing only IAB nodes in a standalone SA deployment Ericsson R2-1903930 CP aspects of IAB nodes Ericsson R2-1903933 Minimizing CN functionalities for IAB network Ericsson R2-1903934 Support for LTE deployment at IAB node sites Ericsson R2-1903935 RLF related notifications in IAB networks Ericsson R2-1903936 IP address assignment for IAB nodes Ericsson R2-1903940 Backhaul RLF handling Intel Corporation R2-1903960 IAB Node Release Procedure Ericsson R2-1903970 Backhaul Channel Setup and Modification Procedure for IAB Ericsson Networks R2-1903971 IAB Node Integration Procedure Ericsson R2-1904172 RLF notification for backhaul link Lenovo, Motorola Mobility R2-1904180 Overview of flow control solutions Samsung R&D Institute UK R2-1904181 IAB RRC state machine Samsung R&D Institute UK R2-1904200 IAB System information handling Sony R2-1904260 Parent node selection for migration Lenovo, Motorola Mobility R2-1904410 BH link RLF notifications Nokia, Nokia Shanghai Bell R2-1904411 Further discussion on BH link RLF handling Nokia, Nokia Shanghai Bell R2-1904427 Downstream notification of BH RLF SHARP Corporation R2-1904430 Access restrictions (barring) in IAB SHARP Corporation R2-1904606 Discussion on IAB BH RLF handling ZTE Corporation, Sanechips R2-1904611 Discussion on BH RLC channel configuration in IAB network ZTE Corporation, Sanechips R2-1904873 Improvements on RLF procedure in IAB ITRI R2-1904905 (De)Prioritizing the Access for IAB Setup Samsung R2-1904975 IAB RRC Connection Establishment Futurewei Technologies R2-1904976 Access Control for IAB MT Futurewei Technologies R2-1904978 Cell Selection and Cell Reselection procedures of IAB Futurewei Technologies R2-1904985 IAB RLC channel management procedure Futurewei Technologies R2-1904987 RRC signaling structure for IAB Futurewei Technologies R2-1904988 Flow control for IAB networks Huawei, HiSilicon R2-1904989 Congestion reporting and handling for IAB networks Futurewei Technologies R2-1905027 Criteria for southbound and northbound backhaul link failure LG Electronics France R2-1905028 Framework of BH RLF notification and recovery LG Electronics France R2-1905029 Inter-node RRC signaling (applicbale for BH RLF notification) LG Electronics France R2-1905043 Access Control for IAB node LG Electronics Inc R2-1905072 BH RLF reporting to IAB donor node LG Electronics Inc. R2-1905103 IAB bearer mapping decision and configuration Futurewei Technologies R2-1905171 Backhaul RLF Recovery Futurewei Technologies*

Although the description above contains many specificities, these should not be construed as limiting the scope of the technology disclosed herein but as merely providing illustrations of some of the presently preferred embodiments of the technology disclosed herein. Thus the scope of the technology disclosed herein should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the technology disclosed herein fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the technology disclosed herein is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” The above-described embodiments could be combined with one another. All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the technology disclosed herein, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.

CROSS REFERENCE

This Nonprovisional application claims priority under 35 U.S.C. § 119 on provisional Application No. 62/842,368 on May 2, 2019, the entire contents of which are hereby incorporated by reference. 

What is claimed is:
 1. A wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through an Integrated Access and Backhaul (IAB) node, the wireless node comprising receiver circuitry configured to: receive from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising an identification of a candidate target cell and configuration parameters for the candidate target cell; receive from the IAB node a notification message comprising information representing a radio condition measured on a path between the IAB node and the wireless access node, and processor circuitry configured to perform, based on the information, a handover to the candidate target cell, using the configuration parameters.
 2. The wireless node of claim 1, wherein the information corresponds to signal strength/quality, and the handover is performed by evaluating the signal strength/quality.
 3. The wireless node of claim 1, wherein the information corresponds to a radio link failure (RLF), and the handover is performed by considering the RLF as if the RLF were occurring at the wireless node.
 4. The wireless node of claim 1, wherein the conditional handover configuration further comprises a triggering condition defining a reception of the notification message as an event to trigger the handover to the candidate target cell.
 5. A method for a wireless node that communicates over a radio interface with a wireless access node of a radio access network (RAN) through at least one Integrated Access and Backhaul (IAB) node, the method comprising receiving from the wireless access node a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising an identification of a candidate target cell and configuration parameters for the candidate target cell; receiving from the IAB node a notification message comprising information representing a radio condition measured on a path between the IAB node and the wireless access node, and; performing, based on the information, a handover to the candidate target cell, using the configuration parameters.
 6. (canceled)
 7. (canceled)
 8. (canceled)
 9. A wireless access node of a radio access network (RAN) that communicates over a radio interface with a wireless node through an Integrated Access and Backhaul (IAB) node, the wireless access node comprising: processor circuitry configured to generate a reconfiguration message comprising a conditional handover configuration, the conditional handover configuration comprising an identification of a candidate target cell and configuration parameters for the candidate target cell; transmitter circuitry configured to transmit the reconfiguration message to the wireless node; wherein the identification of a candidate target cell and information are used by the wireless node to perform a handover to the candidate target cell, using the configuration parameters, the information representing a radio condition measured on a path between the IAB node and the wireless access node, and; the information is included in a notification message sent to the wireless node by the IAB node.
 10. The wireless access node of claim 9, wherein the information corresponds to signal strength/quality, and the handover is performed by evaluating the signal strength/quality.
 11. The wireless access node of claim 9, wherein the information corresponds to a radio link failure (RLF), and the handover is performed by considering the RLF as if the RLF were occurring at the wireless node.
 12. The wireless access node of claim 9, wherein the conditional handover configuration further comprises a triggering condition defining a reception of the notification message as an event to trigger the handover to the candidate target cell.
 13. (canceled)
 14. (canceled)
 15. (canceled)
 16. (canceled) 